Add new tests.

test/libsolidity/ASTJSON/abstract_contract.json

@@ -0,0 +1,72 @@
+{
+	"absolutePath" : "a",
+	"exportedSymbols" : 
+	{
+		"C" : 
+		[
+			5
+		]
+	},
+	"id" : 6,
+	"nodeType" : "SourceUnit",
+	"nodes" : 
+	[
+		{
+			"abstract" : true,
+			"baseContracts" : [],
+			"contractDependencies" : [],
+			"contractKind" : "contract",
+			"documentation" : null,
+			"fullyImplemented" : true,
+			"id" : 5,
+			"linearizedBaseContracts" : 
+			[
+				5
+			],
+			"name" : "C",
+			"nodeType" : "ContractDefinition",
+			"nodes" : 
+			[
+				{
+					"body" : 
+					{
+						"id" : 3,
+						"nodeType" : "Block",
+						"src" : "44:4:1",
+						"statements" : []
+					},
+					"documentation" : null,
+					"id" : 4,
+					"implemented" : true,
+					"kind" : "constructor",
+					"modifiers" : [],
+					"name" : "",
+					"nodeType" : "FunctionDefinition",
+					"overrides" : null,
+					"parameters" : 
+					{
+						"id" : 1,
+						"nodeType" : "ParameterList",
+						"parameters" : [],
+						"src" : "34:2:1"
+					},
+					"returnParameters" : 
+					{
+						"id" : 2,
+						"nodeType" : "ParameterList",
+						"parameters" : [],
+						"src" : "44:0:1"
+					},
+					"scope" : 5,
+					"src" : "23:25:1",
+					"stateMutability" : "nonpayable",
+					"superFunction" : null,
+					"visibility" : "public"
+				}
+			],
+			"scope" : 6,
+			"src" : "0:50:1"
+		}
+	],
+	"src" : "0:51:1"
+}

test/libsolidity/ASTJSON/abstract_contract.sol

@@ -0,0 +1,6 @@
+abstract contract C {
+	constructor() public {
+	}
+}
+
+// ----

test/libsolidity/ASTJSON/abstract_contract_legacy.json

@@ -0,0 +1,112 @@
+{
+	"attributes" : 
+	{
+		"absolutePath" : "a",
+		"exportedSymbols" : 
+		{
+			"C" : 
+			[
+				5
+			]
+		}
+	},
+	"children" : 
+	[
+		{
+			"attributes" : 
+			{
+				"abstract" : true,
+				"baseContracts" : 
+				[
+					null
+				],
+				"contractDependencies" : 
+				[
+					null
+				],
+				"contractKind" : "contract",
+				"documentation" : null,
+				"fullyImplemented" : true,
+				"linearizedBaseContracts" : 
+				[
+					5
+				],
+				"name" : "C",
+				"scope" : 6
+			},
+			"children" : 
+			[
+				{
+					"attributes" : 
+					{
+						"documentation" : null,
+						"implemented" : true,
+						"isConstructor" : true,
+						"kind" : "constructor",
+						"modifiers" : 
+						[
+							null
+						],
+						"name" : "",
+						"overrides" : null,
+						"scope" : 5,
+						"stateMutability" : "nonpayable",
+						"superFunction" : null,
+						"visibility" : "public"
+					},
+					"children" : 
+					[
+						{
+							"attributes" : 
+							{
+								"parameters" : 
+								[
+									null
+								]
+							},
+							"children" : [],
+							"id" : 1,
+							"name" : "ParameterList",
+							"src" : "34:2:1"
+						},
+						{
+							"attributes" : 
+							{
+								"parameters" : 
+								[
+									null
+								]
+							},
+							"children" : [],
+							"id" : 2,
+							"name" : "ParameterList",
+							"src" : "44:0:1"
+						},
+						{
+							"attributes" : 
+							{
+								"statements" : 
+								[
+									null
+								]
+							},
+							"children" : [],
+							"id" : 3,
+							"name" : "Block",
+							"src" : "44:4:1"
+						}
+					],
+					"id" : 4,
+					"name" : "FunctionDefinition",
+					"src" : "23:25:1"
+				}
+			],
+			"id" : 5,
+			"name" : "ContractDefinition",
+			"src" : "0:50:1"
+		}
+	],
+	"id" : 6,
+	"name" : "SourceUnit",
+	"src" : "0:51:1"
+}

test/libsolidity/syntaxTests/abstract/abstract_abstract.sol

@@ -0,0 +1,3 @@
+abstract abstract contract A { constructor() public {} }
+// ----
+// ParserError: (9-17): Contract expected.

test/libsolidity/syntaxTests/abstract/contract.sol

@@ -0,0 +1 @@
+abstract contract A { constructor() public {} }

test/libsolidity/syntaxTests/abstract/interface.sol

@@ -0,0 +1,3 @@
+abstract interface A { }
+// ----
+// ParserError: (0-8): Only contracts can be abstract.

test/libsolidity/syntaxTests/abstract/library.sol

@@ -0,0 +1,3 @@
+abstract library A { }
+// ----
+// ParserError: (0-8): Only contracts can be abstract.

test/libsolidity/syntaxTests/abstract/unimplemented_functions.sol

@@ -0,0 +1,5 @@
+contract A {
+    function a() public;
+}
+// ----
+// TypeError: (0-39): Contract "A" should be marked as abstract.

test/libsolidity/syntaxTests/abstract/unimplemented_functions_inherited.sol

@@ -0,0 +1,7 @@
+abstract contract A {
+    function a() public;
+}
+contract B is A {
+}
+// ----
+// TypeError: (49-68): Contract "B" should be marked as abstract.