Moved fetcher to generic directory (methods have to remain public since it is in seperate package now), added FetchHash method, created ERC20 and generic getters which call the fetcher with specific contract methods (GetTotalSupply, GetBalance, GetAllowance for ERC20 getter, and GetOwner, GetStoppedStatus, GetStringName, GetHashName, GetStringSymbol, GetHashSymbol, and GetDecimals for generic getter). Getter tests cover all but GetBalance and GetAllowance, and also cover all of the Fetcher methods- but with only nil methodArgs. GetAllowance and GetBalance tests are not working against infura and these are the only contract method calls with arguments passed in so I suspect this might be where the issue lies. Have tested GetBalance using previous version of FetchContractData without the variadic input to the Pack method and it fails with the same error so I don’t think it is due to those changes.

examples/erc20_watcher/every_block/every_block_suite_test.go

@@ -25,7 +25,7 @@ import (
 
 func TestEveryBlock(t *testing.T) {
 	RegisterFailHandler(Fail)
-	RunSpecs(t, "EveryBlock Suite")
+	RunSpecs(t, "ERC20 EveryBlock Suite")
 }
 
 var _ = BeforeSuite(func() {

examples/erc20_watcher/every_block/fetcher_test.go

@@ -1,176 +0,0 @@
-// Copyright 2018 Vulcanize
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package every_block_test
-
-import (
-	"math/big"
-
-	"github.com/ethereum/go-ethereum/ethclient"
-	"github.com/ethereum/go-ethereum/rpc"
-	. "github.com/onsi/ginkgo"
-	. "github.com/onsi/gomega"
-
-	"github.com/vulcanize/vulcanizedb/examples/constants"
-	"github.com/vulcanize/vulcanizedb/examples/erc20_watcher/every_block"
-	"github.com/vulcanize/vulcanizedb/pkg/fakes"
-	"github.com/vulcanize/vulcanizedb/pkg/geth"
-	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
-	rpc2 "github.com/vulcanize/vulcanizedb/pkg/geth/converters/rpc"
-	"github.com/vulcanize/vulcanizedb/pkg/geth/node"
-	"github.com/ethereum/go-ethereum/common"
-)
-
-var _ = Describe("ERC20 Fetcher", func() {
-	blockNumber := int64(5502914)
-
-	Describe("totalSupply", func() {
-		It("fetches total supply data from the blockchain with the correct arguments", func() {
-			fakeBlockChain := fakes.NewMockBlockChain()
-			testFetcher := every_block.NewFetcher(fakeBlockChain)
-			testAbi := "testAbi"
-			testContractAddress := "testContractAddress"
-
-			_, err := testFetcher.FetchBigInt("totalSupply", testAbi, testContractAddress, blockNumber, nil)
-
-			Expect(err).NotTo(HaveOccurred())
-			expectedResult := big.Int{}
-			expected := &expectedResult
-			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "totalSupply", nil, &expected, blockNumber)
-		})
-
-		It("fetches dai token's total supply at the given block height", func() {
-			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
-			rawRpcClient, err := rpc.Dial(infuraIPC)
-			Expect(err).NotTo(HaveOccurred())
-			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
-			ethClient := ethclient.NewClient(rawRpcClient)
-			blockChainClient := client.NewEthClient(ethClient)
-			node := node.MakeNode(rpcClient)
-			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
-			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
-			realFetcher := every_block.NewFetcher(blockChain)
-			result, err := realFetcher.FetchBigInt("totalSupply", constants.DaiAbiString, constants.DaiContractAddress, blockNumber, nil)
-
-			Expect(err).NotTo(HaveOccurred())
-			expectedResult := big.Int{}
-			expectedResult.SetString("27647235749155415536952630", 10)
-			Expect(result).To(Equal(expectedResult))
-		})
-
-		It("returns an error if the call to the blockchain fails", func() {
-			blockChain := fakes.NewMockBlockChain()
-			blockChain.SetFetchContractDataErr(fakes.FakeError)
-			errorFetcher := every_block.NewFetcher(blockChain)
-			result, err := errorFetcher.FetchBigInt("totalSupply", "", "", 0, nil)
-
-			Expect(result.String()).To(Equal("0"))
-			Expect(err).To(HaveOccurred())
-			Expect(err.Error()).To(ContainSubstring("totalSupply"))
-			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
-		})
-	})
-
-	Describe("stopped", func() {
-		It("checks whether or not the contract has been stopped", func() {
-			fakeBlockChain := fakes.NewMockBlockChain()
-			testFetcher := every_block.NewFetcher(fakeBlockChain)
-			testAbi := "testAbi"
-			testContractAddress := "testContractAddress"
-
-			_, err := testFetcher.FetchBool("stopped", testAbi, testContractAddress, blockNumber, nil)
-
-			Expect(err).NotTo(HaveOccurred())
-			var expectedResult bool
-			expected := &expectedResult
-			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "stopped", nil, &expected, blockNumber)
-		})
-
-		It("fetches dai token's stopped status at the given block height", func() {
-			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
-			rawRpcClient, err := rpc.Dial(infuraIPC)
-			Expect(err).NotTo(HaveOccurred())
-			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
-			ethClient := ethclient.NewClient(rawRpcClient)
-			blockChainClient := client.NewEthClient(ethClient)
-			node := node.MakeNode(rpcClient)
-			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
-			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
-			realFetcher := every_block.NewFetcher(blockChain)
-			result, err := realFetcher.FetchBool("stopped", constants.DaiAbiString, constants.DaiContractAddress, blockNumber, nil)
-
-			Expect(err).NotTo(HaveOccurred())
-			Expect(result).To(Equal(false))
-		})
-
-		It("returns an error if the call to the blockchain fails", func() {
-			blockChain := fakes.NewMockBlockChain()
-			blockChain.SetFetchContractDataErr(fakes.FakeError)
-			errorFetcher := every_block.NewFetcher(blockChain)
-			result, err := errorFetcher.FetchBool("stopped", "", "", 0, nil)
-
-			Expect(result).To(Equal(false))
-			Expect(err).To(HaveOccurred())
-			Expect(err.Error()).To(ContainSubstring("stopped"))
-			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
-		})
-	})
-
-	Describe("owner", func() {
-		It("checks what the contract's owner address is", func() {
-			fakeBlockChain := fakes.NewMockBlockChain()
-			testFetcher := every_block.NewFetcher(fakeBlockChain)
-			testAbi := "testAbi"
-			testContractAddress := "testContractAddress"
-
-			_, err := testFetcher.FetchAddress("owner", testAbi, testContractAddress, blockNumber, nil)
-
-			Expect(err).NotTo(HaveOccurred())
-			var expectedResult common.Address
-			expected := &expectedResult
-			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "owner", nil, &expected, blockNumber)
-		})
-
-		It("fetches dai token's owner address at the given block height", func() {
-			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
-			rawRpcClient, err := rpc.Dial(infuraIPC)
-			Expect(err).NotTo(HaveOccurred())
-			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
-			ethClient := ethclient.NewClient(rawRpcClient)
-			blockChainClient := client.NewEthClient(ethClient)
-			node := node.MakeNode(rpcClient)
-			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
-			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
-			realFetcher := every_block.NewFetcher(blockChain)
-			result, err := realFetcher.FetchAddress("owner", constants.DaiAbiString, constants.DaiContractAddress, blockNumber, nil)
-
-			Expect(err).NotTo(HaveOccurred())
-			expectedResult := common.HexToAddress("0x0000000000000000000000000000000000000000")
-			Expect(result).To(Equal(expectedResult))
-		})
-
-		It("returns an error if the call to the blockchain fails", func() {
-			blockChain := fakes.NewMockBlockChain()
-			blockChain.SetFetchContractDataErr(fakes.FakeError)
-			errorFetcher := every_block.NewFetcher(blockChain)
-			result, err := errorFetcher.FetchAddress("owner", "", "", 0, nil)
-
-			expectedResult :=  new(common.Address)
-			Expect(result).To(Equal(*expectedResult))
-			Expect(err).To(HaveOccurred())
-			Expect(err.Error()).To(ContainSubstring("owner"))
-			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
-		})
-	})
-})

examples/erc20_watcher/every_block/getter.go

@@ -0,0 +1,64 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy og the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS Og ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package every_block
+
+import (
+	"math/big"
+
+	"github.com/vulcanize/vulcanizedb/examples/generic"
+	"github.com/vulcanize/vulcanizedb/pkg/core"
+)
+
+// Getter serves as a higher level data fetcher that invokes its underlying Fetcher methods for a given contract method
+
+// Interface definition for a Getter
+type ERC20GetterInterface interface {
+	GetTotalSupply(contractAbi, contractAddress string, blockNumber int64) (big.Int, error)
+	GetBalance(contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error)
+	GetAllowance(contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error)
+	GetBlockChain() core.BlockChain
+}
+
+// Getter struct
+type Getter struct {
+	fetcher generic.Fetcher
+}
+
+// Initializes and returns a Getter with the given blockchain
+func NewGetter(blockChain core.BlockChain) Getter {
+	return Getter{
+		fetcher: generic.Fetcher{
+			BlockChain: blockChain,
+		},
+	}
+}
+
+// Public getter methods for calling contract methods
+func (g Getter) GetTotalSupply(contractAbi, contractAddress string, blockNumber int64) (big.Int, error) {
+	return g.fetcher.FetchBigInt("totalSupply", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetBalance(contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error) {
+	return g.fetcher.FetchBigInt("balanceOf", contractAbi, contractAddress, blockNumber, methodArgs)
+}
+
+func (g Getter) GetAllowance(contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error) {
+	return g.fetcher.FetchBigInt("allowance", contractAbi, contractAddress, blockNumber, methodArgs)
+}
+
+// Method to retrieve the Getter's blockchain
+func (g Getter) GetBlockChain() core.BlockChain {
+	return g.fetcher.BlockChain
+}

examples/erc20_watcher/every_block/getter_test.go

@@ -0,0 +1,83 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package every_block_test
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/rpc"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"github.com/vulcanize/vulcanizedb/examples/constants"
+	"github.com/vulcanize/vulcanizedb/examples/erc20_watcher/every_block"
+	"github.com/vulcanize/vulcanizedb/pkg/fakes"
+	"github.com/vulcanize/vulcanizedb/pkg/geth"
+	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
+	rpc2 "github.com/vulcanize/vulcanizedb/pkg/geth/converters/rpc"
+	"github.com/vulcanize/vulcanizedb/pkg/geth/node"
+)
+
+var _ = Describe("ERC20 Getter", func() {
+	blockNumber := int64(5502914)
+
+	Describe("totalSupply", func() {
+		It("gets total supply data from the blockchain with the correct arguments", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetTotalSupply(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := big.Int{}
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "totalSupply", nil, &expected, blockNumber)
+		})
+
+		It("gets dai token's total supply at the given block height", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetTotalSupply(constants.DaiAbiString, constants.DaiContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := big.Int{}
+			expectedResult.SetString("27647235749155415536952630", 10)
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetTotalSupply("", "", 0)
+
+			Expect(result.String()).To(Equal("0"))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("totalSupply"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+})

examples/erc20_watcher/every_block/repository_test.go

@@ -192,9 +192,9 @@ func supplyModel(blockNumber int64, tokenAddress, supplyValue string) every_bloc
 
 func createTokenSupplyFor(repository every_block.ERC20TokenRepository, blockNumber int64, tokenAddress string) {
 	err := repository.CreateSupply(every_block.TokenSupply{
-		BlockNumber: blockNumber,
+		BlockNumber:  blockNumber,
 		TokenAddress: tokenAddress,
-		Value: "0",
+		Value:        "0",
 	})
 	Expect(err).NotTo(HaveOccurred())
 }

examples/erc20_watcher/every_block/transformer.go

@@ -25,7 +25,7 @@ import (
 )
 
 type Transformer struct {
-	Fetcher    ERC20FetcherInterface
+	Getter     ERC20GetterInterface
 	Repository ERC20RepositoryInterface
 	Config     erc20_watcher.ContractConfig
 }
@@ -38,11 +38,11 @@ type TokenSupplyTransformerInitializer struct {
 	Config erc20_watcher.ContractConfig
 }
 
-func (i TokenSupplyTransformerInitializer) NewTokenSupplyTransformer(db *postgres.DB, blockchain core.BlockChain) shared.Transformer {
+func (i TokenSupplyTransformerInitializer) NewTokenSupplyTransformer(db *postgres.DB, blockChain core.BlockChain) shared.Transformer {
-	fetcher := NewFetcher(blockchain)
+	getter := NewGetter(blockChain)
 	repository := ERC20TokenRepository{DB: db}
 	transformer := Transformer{
-		Fetcher:    &fetcher,
+		Getter:     &getter,
 		Repository: &repository,
 		Config:     i.Config,
 	}
@@ -51,8 +51,8 @@ func (i TokenSupplyTransformerInitializer) NewTokenSupplyTransformer(db *postgre
 }
 
 const (
-	FetchingBlocksError = "Error fetching missing blocks starting at block number %d: %s"
+	FetchingBlocksError = "Error getting missing blocks starting at block number %d: %s"
-	FetchingSupplyError = "Error fetching supply for block %d: %s"
+	GetSupplyError      = "Error getting supply for block %d: %s"
 	CreateSupplyError   = "Error inserting token_supply for block %d: %s"
 )
 
@@ -74,8 +74,8 @@ func newTransformerError(err error, blockNumber int64, msg string) error {
 
 func (t Transformer) Execute() error {
 	var upperBoundBlock int64
-	blockchain := t.Fetcher.GetBlockChain()
+	blockChain := t.Getter.GetBlockChain()
-	lastBlock := blockchain.LastBlock().Int64()
+	lastBlock := blockChain.LastBlock().Int64()
 
 	if t.Config.LastBlock == -1 {
 		upperBoundBlock = lastBlock
@@ -93,14 +93,14 @@ func (t Transformer) Execute() error {
 	}
 
 	// Fetch supply for missing blocks
-	log.Printf("Fetching totalSupply for %d blocks", len(blocks))
+	log.Printf("Gets totalSupply for %d blocks", len(blocks))
 
 	// For each block missing total supply, create supply model and feed the missing data into the repository
 	for _, blockNumber := range blocks {
-		totalSupply, err := t.Fetcher.FetchBigInt("totalSupply", t.Config.Abi, t.Config.Address, blockNumber, nil)
+		totalSupply, err := t.Getter.GetTotalSupply(t.Config.Abi, t.Config.Address, blockNumber)
 
 		if err != nil {
-			return newTransformerError(err, blockNumber, FetchingSupplyError)
+			return newTransformerError(err, blockNumber, GetSupplyError)
 		}
 		// Create the supply model
 		model := createTokenSupplyModel(totalSupply, t.Config.Address, blockNumber)

examples/erc20_watcher/every_block/transformer_test.go

@@ -38,7 +38,7 @@ var testContractConfig = erc20_watcher.ContractConfig{
 var config = testContractConfig
 
 var _ = Describe("Everyblock transformer", func() {
-	var fetcher mocks.Fetcher
+	var getter mocks.Getter
 	var repository mocks.ERC20TokenRepository
 	var transformer every_block.Transformer
 	var blockChain *fakes.MockBlockChain
@@ -51,14 +51,14 @@ var _ = Describe("Everyblock transformer", func() {
 	BeforeEach(func() {
 		blockChain = fakes.NewMockBlockChain()
 		blockChain.SetLastBlock(&defaultLastBlock)
-		fetcher = mocks.Fetcher{BlockChain: blockChain}
+		getter = mocks.NewGetter(blockChain)
-		fetcher.SetSupply(initialSupply)
+		getter.Fetcher.SetSupply(initialSupply)
 		repository = mocks.ERC20TokenRepository{}
 		repository.SetMissingSupplyBlocks([]int64{config.FirstBlock})
 		//setting the mock repository to return the first block as the missing blocks
 
 		transformer = every_block.Transformer{
-			Fetcher:    &fetcher,
+			Getter:     &getter,
 			Repository: &repository,
 		}
 		transformer.SetConfiguration(config)
@@ -68,10 +68,10 @@ var _ = Describe("Everyblock transformer", func() {
 		err := transformer.Execute()
 		Expect(err).NotTo(HaveOccurred())
 
-		Expect(len(fetcher.FetchedBlocks)).To(Equal(1))
+		Expect(len(getter.Fetcher.FetchedBlocks)).To(Equal(1))
-		Expect(fetcher.FetchedBlocks).To(ConsistOf(config.FirstBlock))
+		Expect(getter.Fetcher.FetchedBlocks).To(ConsistOf(config.FirstBlock))
-		Expect(fetcher.Abi).To(Equal(config.Abi))
+		Expect(getter.Fetcher.Abi).To(Equal(config.Abi))
-		Expect(fetcher.ContractAddress).To(Equal(config.Address))
+		Expect(getter.Fetcher.ContractAddress).To(Equal(config.Address))
 
 		Expect(repository.StartingBlock).To(Equal(config.FirstBlock))
 		Expect(repository.EndingBlock).To(Equal(config.LastBlock))
@@ -93,10 +93,10 @@ var _ = Describe("Everyblock transformer", func() {
 		err := transformer.Execute()
 		Expect(err).NotTo(HaveOccurred())
 
-		Expect(len(fetcher.FetchedBlocks)).To(Equal(3))
+		Expect(len(getter.Fetcher.FetchedBlocks)).To(Equal(3))
-		Expect(fetcher.FetchedBlocks).To(ConsistOf(config.FirstBlock, config.FirstBlock+1, config.FirstBlock+2))
+		Expect(getter.Fetcher.FetchedBlocks).To(ConsistOf(config.FirstBlock, config.FirstBlock+1, config.FirstBlock+2))
-		Expect(fetcher.Abi).To(Equal(config.Abi))
+		Expect(getter.Fetcher.Abi).To(Equal(config.Abi))
-		Expect(fetcher.ContractAddress).To(Equal(config.Address))
+		Expect(getter.Fetcher.ContractAddress).To(Equal(config.Address))
 
 		Expect(len(repository.TotalSuppliesCreated)).To(Equal(3))
 		Expect(repository.TotalSuppliesCreated[0].Value).To(Equal(initialSupplyPlusOne))
@@ -110,9 +110,9 @@ var _ = Describe("Everyblock transformer", func() {
 		err := transformer.Execute()
 		Expect(err).NotTo(HaveOccurred())
 
-		Expect(fetcher.FetchedBlocks).To(ConsistOf(testContractConfig.FirstBlock))
+		Expect(getter.Fetcher.FetchedBlocks).To(ConsistOf(testContractConfig.FirstBlock))
-		Expect(fetcher.Abi).To(Equal(testContractConfig.Abi))
+		Expect(getter.Fetcher.Abi).To(Equal(testContractConfig.Abi))
-		Expect(fetcher.ContractAddress).To(Equal(testContractConfig.Address))
+		Expect(getter.Fetcher.ContractAddress).To(Equal(testContractConfig.Address))
 
 		Expect(repository.StartingBlock).To(Equal(testContractConfig.FirstBlock))
 		Expect(repository.EndingBlock).To(Equal(testContractConfig.LastBlock))
@@ -146,22 +146,22 @@ var _ = Describe("Everyblock transformer", func() {
 		failureRepository := mocks.FailureRepository{}
 		failureRepository.SetMissingSupplyBlocksFail(true)
 		transformer = every_block.Transformer{
-			Fetcher:    &fetcher,
+			Getter:     &getter,
 			Repository: &failureRepository,
 		}
 		err := transformer.Execute()
 		Expect(err).To(HaveOccurred())
 		Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
-		Expect(err.Error()).To(ContainSubstring("fetching missing blocks"))
+		Expect(err.Error()).To(ContainSubstring("getting missing blocks"))
 	})
 
 	It("returns an error if the call to the blockChain fails", func() {
 		failureBlockchain := fakes.NewMockBlockChain()
 		failureBlockchain.SetLastBlock(&defaultLastBlock)
 		failureBlockchain.SetFetchContractDataErr(fakes.FakeError)
-		fetcher := every_block.NewFetcher(failureBlockchain)
+		getter := every_block.NewGetter(failureBlockchain)
 		transformer = every_block.Transformer{
-			Fetcher:    &fetcher,
+			Getter:     &getter,
 			Repository: &repository,
 		}
 		err := transformer.Execute()
@@ -176,7 +176,7 @@ var _ = Describe("Everyblock transformer", func() {
 		failureRepository.SetCreateSupplyFail(true)
 
 		transformer = every_block.Transformer{
-			Fetcher:    &fetcher,
+			Getter:     &getter,
 			Repository: &failureRepository,
 		}
 		err := transformer.Execute()

examples/generic/every_block/every_block_suite_test.go

@@ -0,0 +1,33 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package every_block_test
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"io/ioutil"
+	"log"
+)
+
+func TestEveryBlock(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Generic EveryBlock Suite")
+}
+
+var _ = BeforeSuite(func() {
+	log.SetOutput(ioutil.Discard)
+})

examples/generic/every_block/getter.go

@@ -0,0 +1,84 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package every_block
+
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/vulcanize/vulcanizedb/examples/generic"
+	"github.com/vulcanize/vulcanizedb/pkg/core"
+	"math/big"
+)
+
+// Getter serves as a higher level data fetcher that invokes its underlying Fetcher methods for a given contract method
+
+// Interface definition for a Getter
+type GenericGetterInterface interface {
+	GetOwner(contractAbi, contractAddress string, blockNumber int64) (common.Address, error)
+	GetStoppedStatus(contractAbi, contractAddress string, blockNumber int64) (bool, error)
+	GetStringName(contractAbi, contractAddress string, blockNumber int64) (string, error)
+	GetHashName(contractAbi, contractAddress string, blockNumber int64) (common.Hash, error)
+	GetStringSymbol(contractAbi, contractAddress string, blockNumber int64) (string, error)
+	GetHashSymbol(contractAbi, contractAddress string, blockNumber int64) (common.Hash, error)
+	GetDecimals(contractAbi, contractAddress string, blockNumber int64) (big.Int, error)
+	GetBlockChain() core.BlockChain
+}
+
+// Getter struct
+type Getter struct {
+	fetcher generic.Fetcher // Underlying Fetcher
+}
+
+// Initializes and returns a Getter with the given blockchain
+func NewGetter(blockChain core.BlockChain) Getter {
+	return Getter{
+		fetcher: generic.Fetcher{
+			BlockChain: blockChain,
+		},
+	}
+}
+
+// Public getter methods for calling contract methods
+func (g Getter) GetOwner(contractAbi, contractAddress string, blockNumber int64) (common.Address, error) {
+	return g.fetcher.FetchAddress("owner", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetStoppedStatus(contractAbi, contractAddress string, blockNumber int64) (bool, error) {
+	return g.fetcher.FetchBool("stopped", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetStringName(contractAbi, contractAddress string, blockNumber int64) (string, error) {
+	return g.fetcher.FetchString("name", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetHashName(contractAbi, contractAddress string, blockNumber int64) (common.Hash, error) {
+	return g.fetcher.FetchHash("name", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetStringSymbol(contractAbi, contractAddress string, blockNumber int64) (string, error) {
+	return g.fetcher.FetchString("symbol", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetHashSymbol(contractAbi, contractAddress string, blockNumber int64) (common.Hash, error) {
+	return g.fetcher.FetchHash("symbol", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g Getter) GetDecimals(contractAbi, contractAddress string, blockNumber int64) (big.Int, error) {
+	return g.fetcher.FetchBigInt("decimals", contractAbi, contractAddress, blockNumber, nil)
+}
+
+// Method to retrieve the Getter's blockchain
+func (g Getter) GetBlockChain() core.BlockChain {
+	return g.fetcher.BlockChain
+}

examples/generic/every_block/getter_test.go

@@ -0,0 +1,364 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package every_block_test
+
+import (
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/rpc"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/vulcanize/vulcanizedb/examples/constants"
+	"github.com/vulcanize/vulcanizedb/examples/generic/every_block"
+	"github.com/vulcanize/vulcanizedb/pkg/fakes"
+	"github.com/vulcanize/vulcanizedb/pkg/geth"
+	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
+	rpc2 "github.com/vulcanize/vulcanizedb/pkg/geth/converters/rpc"
+	"github.com/vulcanize/vulcanizedb/pkg/geth/node"
+	"math/big"
+)
+
+var _ = Describe("every_block Getter", func() {
+	blockNumber := int64(5502914)
+
+	Describe("stopped", func() {
+		It("checks whether or not the contract has been stopped", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetStoppedStatus(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult bool
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "stopped", nil, &expected, blockNumber)
+		})
+
+		It("gets dai token's stopped status at the given block height", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetStoppedStatus(constants.DaiAbiString, constants.DaiContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			Expect(result).To(Equal(false))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetStoppedStatus("", "", 0)
+
+			Expect(result).To(Equal(false))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("stopped"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+
+	Describe("owner", func() {
+		It("checks what the contract's owner address is", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetOwner(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult common.Address
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "owner", nil, &expected, blockNumber)
+		})
+
+		It("gets dai token's owner address at the given block height", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetOwner(constants.DaiAbiString, constants.DaiContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := common.HexToAddress("0x0000000000000000000000000000000000000000")
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetOwner("", "", 0)
+
+			expectedResult := new(common.Address)
+			Expect(result).To(Equal(*expectedResult))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("owner"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+
+	Describe("hash name", func() {
+		It("checks the contract's name", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetHashName(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult common.Hash
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "name", nil, &expected, blockNumber)
+		})
+
+		It("gets dai token's name at the given blockheight", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetHashName(constants.DaiAbiString, constants.DaiContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := common.HexToHash("0x44616920537461626c65636f696e2076312e3000000000000000000000000000")
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetHashName("", "", 0)
+
+			expectedResult := new(common.Hash)
+			Expect(result).To(Equal(*expectedResult))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("name"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+
+	Describe("hash symbol", func() {
+		It("checks the contract's symbol", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetHashSymbol(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult common.Hash
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "symbol", nil, &expected, blockNumber)
+		})
+
+		It("gets dai token's symbol at the given blockheight", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetHashSymbol(constants.DaiAbiString, constants.DaiContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := common.HexToHash("0x4441490000000000000000000000000000000000000000000000000000000000")
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetHashSymbol("", "", 0)
+
+			expectedResult := new(common.Hash)
+			Expect(result).To(Equal(*expectedResult))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("symbol"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+
+	Describe("decimals", func() {
+		It("checks what the token's number of decimals", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetDecimals(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult big.Int
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "decimals", nil, &expected, blockNumber)
+		})
+
+		It("gets dai token's number of decimals at the given block height", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetDecimals(constants.DaiAbiString, constants.DaiContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := big.Int{}
+			expectedResult.SetString("18", 10)
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetDecimals("", "", 0)
+
+			expectedResult := new(big.Int)
+			Expect(result).To(Equal(*expectedResult))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("decimals"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+
+	Describe("string name", func() {
+		It("checks the contract's name", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetStringName(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult string
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "name", nil, &expected, blockNumber)
+		})
+
+		It("gets tusd token's name at the given blockheight", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetStringName(constants.TusdAbiString, constants.TusdContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := "TrueUSD"
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetStringName("", "", 0)
+
+			expectedResult := new(string)
+			Expect(result).To(Equal(*expectedResult))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("name"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+
+	Describe("string symbol", func() {
+		It("checks the contract's symbol", func() {
+			fakeBlockChain := fakes.NewMockBlockChain()
+			testGetter := every_block.NewGetter(fakeBlockChain)
+			testAbi := "testAbi"
+			testContractAddress := "testContractAddress"
+
+			_, err := testGetter.GetStringSymbol(testAbi, testContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			var expectedResult string
+			expected := &expectedResult
+			fakeBlockChain.AssertFetchContractDataCalledWith(testAbi, testContractAddress, "symbol", nil, &expected, blockNumber)
+		})
+
+		It("gets tusd token's symbol at the given blockheight", func() {
+			infuraIPC := "https://mainnet.infura.io/v3/b09888c1113640cc9ab42750ce750c05"
+			rawRpcClient, err := rpc.Dial(infuraIPC)
+			Expect(err).NotTo(HaveOccurred())
+			rpcClient := client.NewRpcClient(rawRpcClient, infuraIPC)
+			ethClient := ethclient.NewClient(rawRpcClient)
+			blockChainClient := client.NewEthClient(ethClient)
+			node := node.MakeNode(rpcClient)
+			transactionConverter := rpc2.NewRpcTransactionConverter(ethClient)
+			blockChain := geth.NewBlockChain(blockChainClient, node, transactionConverter)
+			realGetter := every_block.NewGetter(blockChain)
+			result, err := realGetter.GetStringName(constants.TusdAbiString, constants.TusdContractAddress, blockNumber)
+
+			Expect(err).NotTo(HaveOccurred())
+			expectedResult := "TrueUSD"
+			Expect(result).To(Equal(expectedResult))
+		})
+
+		It("returns an error if the call to the blockchain fails", func() {
+			blockChain := fakes.NewMockBlockChain()
+			blockChain.SetFetchContractDataErr(fakes.FakeError)
+			errorGetter := every_block.NewGetter(blockChain)
+			result, err := errorGetter.GetStringSymbol("", "", 0)
+
+			expectedResult := new(string)
+			Expect(result).To(Equal(*expectedResult))
+			Expect(err).To(HaveOccurred())
+			Expect(err.Error()).To(ContainSubstring("symbol"))
+			Expect(err.Error()).To(ContainSubstring(fakes.FakeError.Error()))
+		})
+	})
+})

examples/generic/fetcher.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package every_block
+package generic
 
 import (
 	"fmt"
@@ -23,26 +23,28 @@ import (
 	"github.com/vulcanize/vulcanizedb/pkg/core"
 )
 
+// Fetcher serves as the lower level data fetcher that calls the underlying
+// blockchain's FetchConctractData method for a given return type
+
 // Interface definition for a Fetcher
-type ERC20FetcherInterface interface {
+type FetcherInterface interface {
 	FetchBigInt(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error)
 	FetchBool(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (bool, error)
 	FetchAddress(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (common.Address, error)
-	GetBlockChain() core.BlockChain
+	FetchString(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (string, error)
+	FetchHash(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (common.Hash, error)
 }
 
-// Initializes and returns a Fetcher with the given blockchain
+// Used to create a new Fetcher error for a given error and fetch method
-func NewFetcher(blockChain core.BlockChain) Fetcher {
+func newFetcherError(err error, fetchMethod string) *fetcherError {
-	return Fetcher{
+	e := fetcherError{err.Error(), fetchMethod}
-		BlockChain: blockChain,
+	log.Println(e.Error())
-	}
+	return &e
 }
 
 // Fetcher struct
 type Fetcher struct {
-	BlockChain      core.BlockChain
+	BlockChain core.BlockChain // Underyling Blockchain
-	ContractAbi     string
-	ContractAddress string
 }
 
 // Fetcher error
@@ -56,14 +58,9 @@ func (fe *fetcherError) Error() string {
 	return fmt.Sprintf("Error fetching %s: %s", fe.fetchMethod, fe.err)
 }
 
-// Used to create a new Fetcher error for a given error and fetch method
+//  Generic Fetcher methods used by Getters to call contract methods
-func newFetcherError(err error, fetchMethod string) *fetcherError {
-	e := fetcherError{err.Error(), fetchMethod}
-	log.Println(e.Error())
-	return &e
-}
 
-// Method used to fetch big.Int result from contract
+// Method used to fetch big.Int value from contract
 func (f Fetcher) FetchBigInt(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error) {
 	var result = new(big.Int)
 	err := f.BlockChain.FetchContractData(contractAbi, contractAddress, method, methodArgs, &result, blockNumber)
@@ -75,7 +72,7 @@ func (f Fetcher) FetchBigInt(method, contractAbi, contractAddress string, blockN
 	return *result, nil
 }
 
-// Method used to fetch bool result from contract
+// Method used to fetch bool value from contract
 func (f Fetcher) FetchBool(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (bool, error) {
 	var result = new(bool)
 	err := f.BlockChain.FetchContractData(contractAbi, contractAddress, method, methodArgs, &result, blockNumber)
@@ -87,7 +84,7 @@ func (f Fetcher) FetchBool(method, contractAbi, contractAddress string, blockNum
 	return *result, nil
 }
 
-// Method used to fetch address result from contract
+// Method used to fetch address value from contract
 func (f Fetcher) FetchAddress(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (common.Address, error) {
 	var result = new(common.Address)
 	err := f.BlockChain.FetchContractData(contractAbi, contractAddress, method, methodArgs, &result, blockNumber)
@@ -99,7 +96,26 @@ func (f Fetcher) FetchAddress(method, contractAbi, contractAddress string, block
 	return *result, nil
 }
 
-// Getter method for Fetcher's blockchain
+// Method used to fetch string value from contract
-func (f Fetcher) GetBlockChain() core.BlockChain {
+func (f Fetcher) FetchString(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (string, error) {
-	return f.BlockChain
+	var result = new(string)
+	err := f.BlockChain.FetchContractData(contractAbi, contractAddress, method, methodArgs, &result, blockNumber)
+
+	if err != nil {
+		return *result, newFetcherError(err, method)
+	}
+
+	return *result, nil
+}
+
+// Method used to fetch hash value from contract
+func (f Fetcher) FetchHash(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (common.Hash, error) {
+	var result = new(common.Hash)
+	err := f.BlockChain.FetchContractData(contractAbi, contractAddress, method, methodArgs, &result, blockNumber)
+
+	if err != nil {
+		return *result, newFetcherError(err, method)
+	}
+
+	return *result, nil
 }

examples/mocks/mocks.go

@@ -33,6 +33,12 @@ type Fetcher struct {
 	supply          big.Int
 	balance         map[string]*big.Int
 	allowance       map[string]map[string]*big.Int
+	owner           common.Address
+	stopped         bool
+	stringName      string
+	hashName        common.Hash
+	stringSymbol    string
+	hashSymbol      common.Hash
 }
 
 func (f *Fetcher) SetSupply(supply string) {
@@ -58,7 +64,7 @@ func (f *Fetcher) FetchBigInt(method, contractAbi, contractAddress string, block
 	}
 
 	if method == "balanceOf" {
-		rfl := reflect.ValueOf(methodArgs).Field(0)
+		rfl := reflect.ValueOf(methodArgs[0])
 		tokenHolderAddr := rfl.Interface().(string)
 		pnt := f.balance[tokenHolderAddr]
 		f.balance[tokenHolderAddr].Add(pnt, accumulator)
@@ -67,8 +73,8 @@ func (f *Fetcher) FetchBigInt(method, contractAbi, contractAddress string, block
 	}
 
 	if method == "allowance" {
-		rfl1 := reflect.ValueOf(methodArgs).Field(0)
+		rfl1 := reflect.ValueOf(methodArgs[0])
-		rfl2 := reflect.ValueOf(methodArgs).Field(1)
+		rfl2 := reflect.ValueOf(methodArgs[1])
 		tokenHolderAddr := rfl1.Interface().(string)
 		spenderAddr := rfl2.Interface().(string)
 		pnt := f.allowance[tokenHolderAddr][spenderAddr]
@@ -82,14 +88,132 @@ func (f *Fetcher) FetchBigInt(method, contractAbi, contractAddress string, block
 }
 
 func (f *Fetcher) FetchBool(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (bool, error) {
-	//TODO: this
+
-	return false, nil
+	f.Abi = contractAbi
+	f.ContractAddress = contractAddress
+	f.FetchedBlocks = append(f.FetchedBlocks, blockNumber)
+
+	b := true
+
+	if method == "stopped" {
+		f.stopped = b
+
+		return f.stopped, nil
+	}
+
+	return false, errors.New("invalid method argument")
 }
 
 func (f *Fetcher) FetchAddress(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (common.Address, error) {
-	//TODO: this
+
-	var adr common.Address
+	f.Abi = contractAbi
-	return adr, nil
+	f.ContractAddress = contractAddress
+	f.FetchedBlocks = append(f.FetchedBlocks, blockNumber)
+
+	adr := common.StringToAddress("test_address")
+
+	if method == "owner" {
+		f.owner = adr
+
+		return f.owner, nil
+	}
+	return common.StringToAddress(""), errors.New("invalid method argument")
+}
+
+func (f *Fetcher) FetchString(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (string, error) {
+
+	f.Abi = contractAbi
+	f.ContractAddress = contractAddress
+	f.FetchedBlocks = append(f.FetchedBlocks, blockNumber)
+
+	if method == "name" {
+		f.stringName = "test_name"
+
+		return f.stringName, nil
+	}
+
+	if method == "symbol" {
+		f.stringSymbol = "test_symbol"
+
+		return f.stringSymbol, nil
+	}
+	return "", errors.New("invalid method argument")
+}
+
+func (f *Fetcher) FetchHash(method, contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (common.Hash, error) {
+
+	f.Abi = contractAbi
+	f.ContractAddress = contractAddress
+	f.FetchedBlocks = append(f.FetchedBlocks, blockNumber)
+
+	if method == "name" {
+		f.hashName = common.StringToHash("test_name")
+
+		return f.hashName, nil
+	}
+
+	if method == "symbol" {
+		f.hashSymbol = common.StringToHash("test_symbol")
+
+		return f.hashSymbol, nil
+	}
+	return common.StringToHash(""), errors.New("invalid method argument")
+}
+
+type Getter struct {
+	Fetcher Fetcher
+}
+
+func NewGetter(blockChain core.BlockChain) Getter {
+	return Getter{
+		Fetcher: Fetcher{
+			BlockChain: blockChain,
+		},
+	}
+}
+
+func (g *Getter) GetTotalSupply(contractAbi, contractAddress string, blockNumber int64) (big.Int, error) {
+	return g.Fetcher.FetchBigInt("totalSupply", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetBalance(contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error) {
+	return g.Fetcher.FetchBigInt("balanceOf", contractAbi, contractAddress, blockNumber, methodArgs)
+}
+
+func (g *Getter) GetAllowance(contractAbi, contractAddress string, blockNumber int64, methodArgs []interface{}) (big.Int, error) {
+	return g.Fetcher.FetchBigInt("allowance", contractAbi, contractAddress, blockNumber, methodArgs)
+}
+
+func (g *Getter) GetOwner(contractAbi, contractAddress string, blockNumber int64) (common.Address, error) {
+	return g.Fetcher.FetchAddress("owner", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetStoppedStatus(contractAbi, contractAddress string, blockNumber int64) (bool, error) {
+	return g.Fetcher.FetchBool("stopped", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetStringName(contractAbi, contractAddress string, blockNumber int64) (string, error) {
+	return g.Fetcher.FetchString("name", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetHashName(contractAbi, contractAddress string, blockNumber int64) (common.Hash, error) {
+	return g.Fetcher.FetchHash("name", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetStringSymbol(contractAbi, contractAddress string, blockNumber int64) (string, error) {
+	return g.Fetcher.FetchString("symbol", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetHashSymbol(contractAbi, contractAddress string, blockNumber int64) (common.Hash, error) {
+	return g.Fetcher.FetchHash("symbol", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetDecimals(contractAbi, contractAddress string, blockNumber int64) (big.Int, error) {
+	return g.Fetcher.FetchBigInt("decimals", contractAbi, contractAddress, blockNumber, nil)
+}
+
+func (g *Getter) GetBlockChain() core.BlockChain {
+	return g.Fetcher.BlockChain
 }
 
 type ERC20TokenRepository struct {

pkg/fakes/mock_blockchain.go

@@ -13,7 +13,7 @@ type MockBlockChain struct {
 	fetchContractDataPassedAbi         string
 	fetchContractDataPassedAddress     string
 	fetchContractDataPassedMethod      string
-	fetchContractDataPassedMethodArgs   []interface{}
+	fetchContractDataPassedMethodArgs  []interface{}
 	fetchContractDataPassedResult      interface{}
 	fetchContractDataPassedBlockNumber int64
 	getBlockByNumberErr                error