tests: fix state test error checking (#25702)

Some tests define an 'expectException' error but the tests runner does not check for conditions where this test value is filled (error expected) but in which no error is returned by the test runner.

An example of this scenario is GeneralStateTests/stTransactionTest/HighGasPrice.json, which expects a 'TR_NoFunds' error, but the test runner does not return any error.

Signed-off-by: meows <b5c6@protonmail.com>

tests/state_test.go

@@ -78,10 +78,6 @@ func TestState(t *testing.T) {
 				t.Run(key+"/trie", func(t *testing.T) {
 					withTrace(t, test.gasLimit(subtest), func(vmconfig vm.Config) error {
 						_, _, err := test.Run(subtest, vmconfig, false)
-						if err != nil && len(test.json.Post[subtest.Fork][subtest.Index].ExpectException) > 0 {
-							// Ignore expected errors (TODO MariusVanDerWijden check error string)
-							return nil
-						}
 						return st.checkFailure(t, err)
 					})
 				})
@@ -93,10 +89,6 @@ func TestState(t *testing.T) {
 								return err
 							}
 						}
-						if err != nil && len(test.json.Post[subtest.Fork][subtest.Index].ExpectException) > 0 {
-							// Ignore expected errors (TODO MariusVanDerWijden check error string)
-							return nil
-						}
 						return st.checkFailure(t, err)
 					})
 				})

tests/state_test_util.go

@@ -159,11 +159,39 @@ func (t *StateTest) Subtests() []StateSubtest {
 	return sub
 }
 
+// checkError checks if the error returned by the state transition matches any expected error.
+// A failing expectation returns a wrapped version of the original error, if any,
+// or a new error detailing the failing expectation.
+// This function does not return or modify the original error, it only evaluates and returns expectations for the error.
+func (t *StateTest) checkError(subtest StateSubtest, err error) error {
+	expectedError := t.json.Post[subtest.Fork][subtest.Index].ExpectException
+	if err == nil && expectedError == "" {
+		return nil
+	}
+	if err == nil && expectedError != "" {
+		return fmt.Errorf("expected error %q, got no error", expectedError)
+	}
+	if err != nil && expectedError == "" {
+		return fmt.Errorf("unexpected error: %w", err)
+	}
+	if err != nil && expectedError != "" {
+		// Ignore expected errors (TODO MariusVanDerWijden check error string)
+		return nil
+	}
+	return nil
+}
+
 // Run executes a specific subtest and verifies the post-state and logs
 func (t *StateTest) Run(subtest StateSubtest, vmconfig vm.Config, snapshotter bool) (*snapshot.Tree, *state.StateDB, error) {
 	snaps, statedb, root, err := t.RunNoVerify(subtest, vmconfig, snapshotter)
+	if checkedErr := t.checkError(subtest, err); checkedErr != nil {
+		return snaps, statedb, checkedErr
+	}
+	// The error has been checked; if it was unexpected, it's already returned.
 	if err != nil {
-		return snaps, statedb, err
+		// Here, an error exists but it was expected.
+		// We do not check the post state or logs.
+		return snaps, statedb, nil
 	}
 	post := t.json.Post[subtest.Fork][subtest.Index]
 	// N.B: We need to do this in a two-step process, because the first Commit takes care
@@ -231,7 +259,8 @@ func (t *StateTest) RunNoVerify(subtest StateSubtest, vmconfig vm.Config, snapsh
 	snapshot := statedb.Snapshot()
 	gaspool := new(core.GasPool)
 	gaspool.AddGas(block.GasLimit())
-	if _, err := core.ApplyMessage(evm, msg, gaspool); err != nil {
+	_, err = core.ApplyMessage(evm, msg, gaspool)
+	if err != nil {
 		statedb.RevertToSnapshot(snapshot)
 	}
 	// Add 0-value mining reward. This only makes a difference in the cases
@@ -244,7 +273,7 @@ func (t *StateTest) RunNoVerify(subtest StateSubtest, vmconfig vm.Config, snapsh
 	statedb.Commit(config.IsEIP158(block.Number()))
 	// And _now_ get the state root
 	root := statedb.IntermediateRoot(config.IsEIP158(block.Number()))
-	return snaps, statedb, root, nil
+	return snaps, statedb, root, err
 }
 
 func (t *StateTest) gasLimit(subtest StateSubtest) uint64 {