tests/compiler/dart2js/type_checker_test.dart

// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import '../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart';
import '../../../sdk/lib/_internal/compiler/implementation/tree/tree.dart';
import '../../../sdk/lib/_internal/compiler/implementation/util/util.dart';
import 'mock_compiler.dart';
import 'parser_helper.dart';

import '../../../sdk/lib/_internal/compiler/implementation/elements/modelx.dart'
    show ElementX;

import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart'
    hide SourceString;

import '../../../sdk/lib/_internal/compiler/implementation/dart_types.dart';

DartType intType;
DartType boolType;
DartType stringType;
DartType doubleType;
DartType objectType;

main() {
  List tests = [testSimpleTypes,
                testReturn,
                testFor,
                testWhile,
                testOperators,
                testConstructorInvocationArgumentCount,
                testConstructorInvocationArgumentTypes,
                testMethodInvocationArgumentCount,
                testMethodInvocations,
                testControlFlow,
                // testNewExpression,
                testConditionalExpression,
                testIfStatement,
                testThis,
                testFunctionSubtyping,
                testFunctionSubtypingOptional,
                testFunctionSubtypingNamed];
  for (Function test in tests) {
    setup();
    test();
  }
}

testSimpleTypes() {
  Expect.equals(intType, analyzeType("3"));
  Expect.equals(boolType, analyzeType("false"));
  Expect.equals(boolType, analyzeType("true"));
  Expect.equals(stringType, analyzeType("'hestfisk'"));
}

testReturn() {
  analyzeTopLevel("void foo() { return 3; }", MessageKind.RETURN_VALUE_IN_VOID);
  analyzeTopLevel("int bar() { return 'hest'; }", MessageKind.NOT_ASSIGNABLE);
  analyzeTopLevel("void baz() { var x; return x; }");
  analyzeTopLevel(returnWithType("int", "'string'"),
                  MessageKind.NOT_ASSIGNABLE);
  analyzeTopLevel(returnWithType("", "'string'"));
  analyzeTopLevel(returnWithType("Object", "'string'"));
  analyzeTopLevel(returnWithType("String", "'string'"));
  analyzeTopLevel(returnWithType("String", null));
  analyzeTopLevel(returnWithType("int", null));
  analyzeTopLevel(returnWithType("void", ""));
  analyzeTopLevel(returnWithType("void", 1), MessageKind.RETURN_VALUE_IN_VOID);
  analyzeTopLevel(returnWithType("void", null));
  analyzeTopLevel(returnWithType("String", ""), MessageKind.RETURN_NOTHING);
  // analyzeTopLevel("String foo() {};"); // Should probably fail.
}

testFor() {
  analyze("for (var x;true;x = x + 1) {}");
  analyze("for (var x;null;x = x + 1) {}");
  analyze("for (var x;0;x = x + 1) {}", MessageKind.NOT_ASSIGNABLE);
  analyze("for (var x;'';x = x + 1) {}", MessageKind.NOT_ASSIGNABLE);

   analyze("for (;true;) {}");
   analyze("for (;null;) {}");
   analyze("for (;0;) {}", MessageKind.NOT_ASSIGNABLE);
   analyze("for (;'';) {}", MessageKind.NOT_ASSIGNABLE);

  // Foreach tests
//  TODO(karlklose): for each is not yet implemented.
//  analyze("{ List<String> strings = ['1','2','3']; " +
//          "for (String s in strings) {} }");
//  analyze("{ List<int> ints = [1,2,3]; for (String s in ints) {} }",
//          MessageKind.NOT_ASSIGNABLE);
//  analyze("for (String s in true) {}", MessageKind.METHOD_NOT_FOUND);
}

testWhile() {
  analyze("while (true) {}");
  analyze("while (null) {}");
  analyze("while (0) {}", MessageKind.NOT_ASSIGNABLE);
  analyze("while ('') {}", MessageKind.NOT_ASSIGNABLE);

  analyze("do {} while (true);");
  analyze("do {} while (null);");
  analyze("do {} while (0);", MessageKind.NOT_ASSIGNABLE);
  analyze("do {} while ('');", MessageKind.NOT_ASSIGNABLE);
  analyze("do { int i = 0.5; } while (true);", MessageKind.NOT_ASSIGNABLE);
  analyze("do { int i = 0.5; } while (null);", MessageKind.NOT_ASSIGNABLE);
}

testOperators() {
  // TODO(karlklose): add the DartC tests for operators when we can parse
  // classes with operators.
  for (final op in ['+', '-', '*', '/', '%', '~/', '|', '&']) {
    analyze("{ var i = 1 ${op} 2; }");
    analyze("{ var i = 1; i ${op}= 2; }");
    analyze("{ int i; var j = (i = true) ${op} 2; }",
            MessageKind.NOT_ASSIGNABLE);
    analyze("{ int i; var j = 1 ${op} (i = true); }",
            MessageKind.NOT_ASSIGNABLE);
  }
  for (final op in ['-', '~']) {
    analyze("{ var i = ${op}1; }");
    analyze("{ int i; var j = ${op}(i = true); }", MessageKind.NOT_ASSIGNABLE);
  }
  for (final op in ['++', '--']) {
    analyze("{ int i = 1; int j = i${op}; }");
    analyze("{ int i = 1; bool j = i${op}; }", MessageKind.NOT_ASSIGNABLE);
    analyze("{ bool b = true; bool j = b${op}; }");
    analyze("{ bool b = true; int j = ${op}b; }");
  }
  for (final op in ['||', '&&']) {
    analyze("{ bool b = (true ${op} false); }");
    analyze("{ int b = true ${op} false; }", MessageKind.NOT_ASSIGNABLE);
    analyze("{ bool b = (1 ${op} false); }", MessageKind.NOT_ASSIGNABLE);
    analyze("{ bool b = (true ${op} 2); }", MessageKind.NOT_ASSIGNABLE);
  }
  for (final op in ['>', '<', '<=', '>=', '==', '!=']) {
    analyze("{ bool b = 1 ${op} 2; }");
    analyze("{ int i = 1 ${op} 2; }", MessageKind.NOT_ASSIGNABLE);
    analyze("{ int i; bool b = (i = true) ${op} 2; }",
            MessageKind.NOT_ASSIGNABLE);
    analyze("{ int i; bool b = 1 ${op} (i = true); }",
            MessageKind.NOT_ASSIGNABLE);
  }
}

void testConstructorInvocationArgumentCount() {
  compiler.parseScript("""
     class C1 { C1(x, y); }
     class C2 { C2(int x, int y); }
  """);
  // calls to untyped constructor C1
  analyze("new C1(1, 2);");
  analyze("new C1();", MessageKind.MISSING_ARGUMENT);
  analyze("new C1(1);", MessageKind.MISSING_ARGUMENT);
  analyze("new C1(1, 2, 3);", MessageKind.ADDITIONAL_ARGUMENT);
  // calls to typed constructor C2
  analyze("new C2(1, 2);");
  analyze("new C2();", MessageKind.MISSING_ARGUMENT);
  analyze("new C2(1);", MessageKind.MISSING_ARGUMENT);
  analyze("new C2(1, 2, 3);", MessageKind.ADDITIONAL_ARGUMENT);
}

void testConstructorInvocationArgumentTypes() {
  compiler.parseScript("""
    class C1 { C1(x); }
    class C2 { C2(int x); }
  """);
  analyze("new C1(42);");
  analyze("new C1('string');");
  analyze("new C2(42);");
  analyze("new C2('string');",
          MessageKind.NOT_ASSIGNABLE);
}

void testMethodInvocationArgumentCount() {
  compiler.parseScript(CLASS_WITH_METHODS);
  final String header = "{ ClassWithMethods c; ";
  analyze("${header}c.untypedNoArgumentMethod(1); }",
          MessageKind.ADDITIONAL_ARGUMENT);
  analyze("${header}c.untypedOneArgumentMethod(); }",
          MessageKind.MISSING_ARGUMENT);
  analyze("${header}c.untypedOneArgumentMethod(1, 1); }",
          MessageKind.ADDITIONAL_ARGUMENT);
  analyze("${header}c.untypedTwoArgumentMethod(); }",
          MessageKind.MISSING_ARGUMENT);
  analyze("${header}c.untypedTwoArgumentMethod(1, 2, 3); }",
          MessageKind.ADDITIONAL_ARGUMENT);
  analyze("${header}c.intNoArgumentMethod(1); }",
          MessageKind.ADDITIONAL_ARGUMENT);
  analyze("${header}c.intOneArgumentMethod(); }",
          MessageKind.MISSING_ARGUMENT);
  analyze("${header}c.intOneArgumentMethod(1, 1); }",
          MessageKind.ADDITIONAL_ARGUMENT);
  analyze("${header}c.intTwoArgumentMethod(); }",
          MessageKind.MISSING_ARGUMENT);
  analyze("${header}c.intTwoArgumentMethod(1, 2, 3); }",
          MessageKind.ADDITIONAL_ARGUMENT);
  // analyze("${header}c.untypedField(); }");

  analyze("${header}c.intOneArgumentOneOptionalMethod(); }",
          [MessageKind.MISSING_ARGUMENT]);
  analyze("${header}c.intOneArgumentOneOptionalMethod(0); }");
  analyze("${header}c.intOneArgumentOneOptionalMethod(0, 1); }");
  analyze("${header}c.intOneArgumentOneOptionalMethod(0, 1, 2); }",
          [MessageKind.ADDITIONAL_ARGUMENT]);
  analyze("${header}c.intOneArgumentOneOptionalMethod(0, 1, c: 2); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intOneArgumentOneOptionalMethod(0, b: 1); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intOneArgumentOneOptionalMethod(a: 0, b: 1); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND,
           MessageKind.NAMED_ARGUMENT_NOT_FOUND,
           MessageKind.MISSING_ARGUMENT]);

  analyze("${header}c.intTwoOptionalMethod(); }");
  analyze("${header}c.intTwoOptionalMethod(0); }");
  analyze("${header}c.intTwoOptionalMethod(0, 1); }");
  analyze("${header}c.intTwoOptionalMethod(0, 1, 2); }",
          [MessageKind.ADDITIONAL_ARGUMENT]);
  analyze("${header}c.intTwoOptionalMethod(a: 0); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intTwoOptionalMethod(0, b: 1); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);

  analyze("${header}c.intOneArgumentOneNamedMethod(); }",
          [MessageKind.MISSING_ARGUMENT]);
  analyze("${header}c.intOneArgumentOneNamedMethod(0); }");
  analyze("${header}c.intOneArgumentOneNamedMethod(0, b: 1); }");
  analyze("${header}c.intOneArgumentOneNamedMethod(b: 1); }",
          [MessageKind.MISSING_ARGUMENT]);
  analyze("${header}c.intOneArgumentOneNamedMethod(0, b: 1, c: 2); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intOneArgumentOneNamedMethod(0, 1); }",
          [MessageKind.ADDITIONAL_ARGUMENT]);
  analyze("${header}c.intOneArgumentOneNamedMethod(0, 1, c: 2); }",
          [MessageKind.ADDITIONAL_ARGUMENT,
           MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intOneArgumentOneNamedMethod(a: 1, b: 1); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND,
           MessageKind.MISSING_ARGUMENT]);

  analyze("${header}c.intTwoNamedMethod(); }");
  analyze("${header}c.intTwoNamedMethod(a: 0); }");
  analyze("${header}c.intTwoNamedMethod(b: 1); }");
  analyze("${header}c.intTwoNamedMethod(a: 0, b: 1); }");
  analyze("${header}c.intTwoNamedMethod(b: 1, a: 0); }");
  analyze("${header}c.intTwoNamedMethod(0); }",
          [MessageKind.ADDITIONAL_ARGUMENT]);
  analyze("${header}c.intTwoNamedMethod(c: 2); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intTwoNamedMethod(a: 0, c: 2); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intTwoNamedMethod(a: 0, b: 1, c: 2); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intTwoNamedMethod(c: 2, b: 1, a: 0); }",
          [MessageKind.NAMED_ARGUMENT_NOT_FOUND]);
  analyze("${header}c.intTwoNamedMethod(0, b: 1); }",
          [MessageKind.ADDITIONAL_ARGUMENT]);
  analyze("${header}c.intTwoNamedMethod(0, 1); }",
          [MessageKind.ADDITIONAL_ARGUMENT,
           MessageKind.ADDITIONAL_ARGUMENT]);
  analyze("${header}c.intTwoNamedMethod(0, c: 2); }",
          [MessageKind.ADDITIONAL_ARGUMENT,
           MessageKind.NAMED_ARGUMENT_NOT_FOUND]);

}

void testMethodInvocations() {
  compiler.parseScript(CLASS_WITH_METHODS);
  final String header = "{ ClassWithMethods c; SubClass d; int i; int j; ";

  analyze("${header}int k = c.untypedNoArgumentMethod(); }");
  analyze("${header}ClassWithMethods x = c.untypedNoArgumentMethod(); }");
  analyze("${header}ClassWithMethods x = d.untypedNoArgumentMethod(); }");
  analyze("${header}int k = d.intMethod(); }");
  analyze("${header}int k = c.untypedOneArgumentMethod(c); }");
  analyze("${header}ClassWithMethods x = c.untypedOneArgumentMethod(1); }");
  analyze("${header}int k = c.untypedOneArgumentMethod('string'); }");
  analyze("${header}int k = c.untypedOneArgumentMethod(i); }");
  analyze("${header}int k = d.untypedOneArgumentMethod(d); }");
  analyze("${header}ClassWithMethods x = d.untypedOneArgumentMethod(1); }");
  analyze("${header}int k = d.untypedOneArgumentMethod('string'); }");
  analyze("${header}int k = d.untypedOneArgumentMethod(i); }");

  analyze("${header}int k = c.untypedTwoArgumentMethod(1, 'string'); }");
  analyze("${header}int k = c.untypedTwoArgumentMethod(i, j); }");
  analyze("${header}ClassWithMethods x = c.untypedTwoArgumentMethod(i, c); }");
  analyze("${header}int k = d.untypedTwoArgumentMethod(1, 'string'); }");
  analyze("${header}int k = d.untypedTwoArgumentMethod(i, j); }");
  analyze("${header}ClassWithMethods x = d.untypedTwoArgumentMethod(i, d); }");

  analyze("${header}int k = c.intNoArgumentMethod(); }");
  analyze("${header}ClassWithMethods x = c.intNoArgumentMethod(); }",
          MessageKind.NOT_ASSIGNABLE);

  analyze("${header}int k = c.intOneArgumentMethod(c); }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("${header}ClassWithMethods x = c.intOneArgumentMethod(1); }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("${header}int k = c.intOneArgumentMethod('string'); }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("${header}int k = c.intOneArgumentMethod(i); }");

  analyze("${header}int k = c.intTwoArgumentMethod(1, 'string'); }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("${header}int k = c.intTwoArgumentMethod(i, j); }");
  analyze("${header}ClassWithMethods x = c.intTwoArgumentMethod(i, j); }",
          MessageKind.NOT_ASSIGNABLE);

  analyze("${header}c.intField(); }", MessageKind.METHOD_NOT_FOUND);
  analyze("${header}d.intField(); }", MessageKind.METHOD_NOT_FOUND);
}

/** Tests analysis of returns (not required by the specification). */
void testControlFlow() {
  analyzeTopLevel("void foo() { if (true) { return; } }");
  analyzeTopLevel("foo() { if (true) { return; } }");
  analyzeTopLevel("int foo() { if (true) { return 1; } }",
                  MessageKind.MAYBE_MISSING_RETURN);
  final bar =
      """void bar() {
        if (true) {
          if (true) { return; } else { return; }
        } else { return; }
      }""";
  analyzeTopLevel(bar);
  analyzeTopLevel("void baz() { return; int i = 1; }",
                  MessageKind.UNREACHABLE_CODE);
  final qux =
      """void qux() {
        if (true) {
          return;
        } else if (true) {
          if (true) {
            return;
          }
          throw 'hest';
        }
        throw 'fisk';
      }""";
  analyzeTopLevel(qux);
  analyzeTopLevel("int hest() {}", MessageKind.MISSING_RETURN);
  final fisk = """int fisk() {
                    if (true) {
                      if (true) { return 1; } else {}
                    } else { return 1; }
                  }""";
  analyzeTopLevel(fisk, MessageKind.MAYBE_MISSING_RETURN);
  analyzeTopLevel("int foo() { while(true) { return 1; } }");
  analyzeTopLevel("int foo() { while(true) { return 1; } return 2; }",
                  MessageKind.UNREACHABLE_CODE);
}

testNewExpression() {
  compiler.parseScript("class A {}");
  analyze("A a = new A();");
  analyze("int i = new A();", MessageKind.NOT_ASSIGNABLE);

// TODO(karlklose): constructors are not yet implemented.
//  compiler.parseScript(
//    "class Foo {\n" +
//    "  Foo(int x) {}\n" +
//    "  Foo.foo() {}\n" +
//    "  Foo.bar([int i = null]) {}\n" +
//    "}\n" +
//    "interface Bar<T> factory Baz {\n" +
//    "  Bar.make();\n" +
//    "}\n" +
//    "class Baz {\n" +
//    "  factory Bar<S>.make(S x) { return null; }\n" +
//    "}");
//
//  analyze("Foo x = new Foo(0);");
//  analyze("Foo x = new Foo();", MessageKind.MISSING_ARGUMENT);
//  analyze("Foo x = new Foo('');", MessageKind.NOT_ASSIGNABLE);
//  analyze("Foo x = new Foo(0, null);", MessageKind.ADDITIONAL_ARGUMENT);
//
//  analyze("Foo x = new Foo.foo();");
//  analyze("Foo x = new Foo.foo(null);", MessageKind.ADDITIONAL_ARGUMENT);
//
//  analyze("Foo x = new Foo.bar();");
//  analyze("Foo x = new Foo.bar(0);");
//  analyze("Foo x = new Foo.bar('');", MessageKind.NOT_ASSIGNABLE);
//  analyze("Foo x = new Foo.bar(0, null);",
//          MessageKind.ADDITIONAL_ARGUMENT);
//
//  analyze("Bar<String> x = new Bar<String>.make('');");
}

testConditionalExpression() {
  analyze("int i = true ? 2 : 1;");
  analyze("int i = true ? 'hest' : 1;");
  analyze("int i = true ? 'hest' : 'fisk';", MessageKind.NOT_ASSIGNABLE);
  analyze("String s = true ? 'hest' : 'fisk';");

  analyze("true ? 1 : 2;");
  analyze("null ? 1 : 2;");
  analyze("0 ? 1 : 2;", MessageKind.NOT_ASSIGNABLE);
  analyze("'' ? 1 : 2;", MessageKind.NOT_ASSIGNABLE);
  analyze("{ int i; true ? i = 2.7 : 2; }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("{ int i; true ? 2 : i = 2.7; }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("{ int i; i = true ? 2.7 : 2; }");
}

testIfStatement() {
  analyze("if (true) {}");
  analyze("if (null) {}");
  analyze("if (0) {}",
  MessageKind.NOT_ASSIGNABLE);
  analyze("if ('') {}",
          MessageKind.NOT_ASSIGNABLE);
  analyze("{ int i = 27; if (true) { i = 2.7; } else {} }",
          MessageKind.NOT_ASSIGNABLE);
  analyze("{ int i = 27; if (true) {} else { i = 2.7; } }",
          MessageKind.NOT_ASSIGNABLE);
}

testThis() {
  String script = "class Foo {}";
  LibraryElement library = mockLibrary(compiler, script);
  compiler.parseScript(script, library);
  ClassElement foo = library.find(const SourceString("Foo"));
  analyzeIn(foo, "{ int i = this; }", MessageKind.NOT_ASSIGNABLE);
  analyzeIn(foo, "{ Object o = this; }");
  analyzeIn(foo, "{ Foo f = this; }");
}

testFunctionSubtyping() {
  // Checks that the type (in1 -> out1) is a subtype of (in2 -> out2).
  bool isSubtype(List<DartType> in1, DartType out1, List<DartType> in2,
                 DartType out2) {
    return compiler.types.isSubtype(
        new FunctionType(null, out1, new Link<DartType>.fromList(in1),
                         const Link<DartType>(),
                         const Link<SourceString>(), const Link<DartType>()),
        new FunctionType(null, out2, new Link<DartType>.fromList(in2),
                         const Link<DartType>(),
                         const Link<SourceString>(), const Link<DartType>()));
  }
  Expect.isTrue(isSubtype([], intType, [], intType));
  Expect.isTrue(isSubtype([], intType, [], objectType));
  Expect.isFalse(isSubtype([], intType, [], doubleType));
  Expect.isTrue(isSubtype([intType], intType, [intType], intType));
  Expect.isTrue(isSubtype([objectType], intType, [intType], objectType));
  Expect.isFalse(isSubtype([intType], intType, [doubleType], intType));
  Expect.isFalse(isSubtype([intType], intType, [intType, intType], intType));
  Expect.isFalse(isSubtype([intType, intType], intType, [intType], intType));
}

testFunctionSubtypingOptional() {
  // Checks whether the type (in1,[opt1] -> void) is a subtype of
  // (in2,[opt2] -> void).
  expect(bool value, List<DartType> in1, List<DartType> opt1,
                     List<DartType> in2, List<DartType> opt2) {
    var fn1 = new FunctionType(null,
        compiler.types.dynamicType,
        new Link<DartType>.fromList(in1),
        new Link<DartType>.fromList(opt1),
        const Link<SourceString>(), const Link<DartType>());
    var fn2 = new FunctionType(null,
        compiler.types.dynamicType,
        new Link<DartType>.fromList(in2),
        new Link<DartType>.fromList(opt2),
        const Link<SourceString>(), const Link<DartType>());
    Expect.equals(value, compiler.types.isSubtype(fn1, fn2), "$fn1 <: $fn2");
  }

  // Test ()->void <: ()->void.
  expect(true, [], [], [], []);
  // Test ([int])->void <: ()->void.
  expect(true, [], [intType], [], []);
  // Test ([int])->void <: (int)->void.
  expect(false, [], [intType], [intType], []);
  // Test (int)->void <: ([int])->void.
  expect(false, [intType], [], [], [intType]);
  // Test ([int])->void <: ([int])->void.
  expect(true, [], [intType], [], [intType]);
  // Test ([Object])->void <: ([int])->void.
  expect(true, [], [objectType], [], [intType]);
  // Test ([int])->void <: ([Object])->void.
  expect(true, [], [intType], [], [objectType]);
  // Test (int,[int])->void <: (int,[int])->void.
  expect(true, [intType], [intType], [intType], [intType]);
  // Test ([int])->void <: ([double])->void.
  expect(false, [], [intType], [], [doubleType]);
  // Test ([int])->void <: ([int,int])->void.
  expect(false, [], [intType], [], [intType, intType]);
  // Test ([int,int])->void <: ([int])->void.
  expect(true, [], [intType, intType], [], [intType]);
  // Test ([Object,int])->void <: ([int])->void.
  expect(true, [], [objectType, intType], [], [intType]);
}


testFunctionSubtypingNamed() {
  // Checks whether the type (in1,{nm1} -> out1) is a subtype of
  // (in2,{nm2} -> out2).
  expect(bool value, List<DartType> in1, Map<String,DartType> nm1,
                     List<DartType> in2, Map<String,DartType> nm2) {

    SourceString convertString(String string) => new SourceString(string);
    int compareString(a, b) => a.compareTo(b);

    Link<SourceString> createNames(Map<String,DartType> nm) {
      List<String> nmSorted = new List<String>.from(nm.keys)..sort();
      List<SourceString> nmSourceStrings =
          nmSorted.map((string) => new SourceString(string)).toList();
      return new Link<SourceString>.fromList(nmSourceStrings);
    }

    Link<DartType> createTypes(Map<String,DartType> nm,
                               Link<SourceString> names) {
      var types = new LinkBuilder<DartType>();
      for (SourceString name in names) {
        types.addLast(nm[name.slowToString()]);
      }
      return types.toLink();
    }

    Link<SourceString> names1 = createNames(nm1);
    Link<DartType> types1 = createTypes(nm1, names1);
    Link<SourceString> names2 = createNames(nm2);
    Link<DartType> types2 = createTypes(nm2, names2);
    var fn1 = new FunctionType(null,
        compiler.types.dynamicType,
        new Link<DartType>.fromList(in1),
        const Link<DartType>(),
        names1, types1);
    var fn2 = new FunctionType(null,
        compiler.types.dynamicType,
        new Link<DartType>.fromList(in2),
        const Link<DartType>(),
        names2, types2);
    Expect.equals(value, compiler.types.isSubtype(fn1, fn2), "$fn1 <: $fn2");
  }

  // Test ()->void <: ()->void.
  expect(true, [], {}, [], {});
  // Test ({int a})->void <: ()->void.
  expect(true, [], {'a': intType}, [], {});
  // Test ({int a})->void <: (int)->void.
  expect(false, [], {'a': intType}, [intType], {});
  // Test (int)->void <: ({int a})->void.
  expect(false, [intType], {}, [], {'a': intType});
  // Test ({int a})->void <: ({int a})->void.
  expect(true, [], {'a': intType}, [], {'a': intType});
  // Test ({int a})->void <: ({int b})->void.
  expect(false, [], {'a': intType}, [], {'b': intType});
  // Test ({Object a})->void <: ({int a})->void.
  expect(true, [], {'a': objectType}, [], {'a': intType});
  // Test ({int a})->void <: ([Object])->void.
  expect(true, [], {'a': intType}, [], {'a': objectType});
  // Test (int,{int a})->void <: (int,{int a})->void.
  expect(true, [intType], {'a': intType}, [intType], {'a': intType});
  // Test ({int a})->void <: ({double a})->void.
  expect(false, [], {'a': intType}, [], {'a': doubleType});
  // Test ({int a})->void <: ({int a,int b})->void.
  expect(false, [], {'a': intType}, [], {'a': intType, 'b': intType});
  // Test ({int a,int b})->void <: ({int a})->void.
  expect(true, [], {'a': intType, 'b': intType}, [], {'a': intType});
  // Test ({int a,int b,int c})->void <: ({int a,int c})->void.
  expect(true, [], {'a': intType, 'b': intType, 'c': intType},
               [], {'a': intType, 'c': intType});
  // Test ({int a,int b,int c})->void <: ({int b,int c})->void.
  expect(true, [], {'a': intType, 'b': intType, 'c': intType},
               [], {'b': intType, 'c': intType});
  // Test ({int a,int b,int c})->void <: ({int c})->void.
  expect(true, [], {'a': intType, 'b': intType, 'c': intType},
               [], {'c': intType});
}


const CLASS_WITH_METHODS = '''
class ClassWithMethods {
  untypedNoArgumentMethod() {}
  untypedOneArgumentMethod(argument) {}
  untypedTwoArgumentMethod(argument1, argument2) {}

  int intNoArgumentMethod() {}
  int intOneArgumentMethod(int argument) {}
  int intTwoArgumentMethod(int argument1, int argument2) {}

  void intOneArgumentOneOptionalMethod(int a, [int b]) {}
  void intTwoOptionalMethod([int a, int b]) {}
  void intOneArgumentOneNamedMethod(int a, {int b}) {}
  void intTwoNamedMethod({int a, int b}) {}

  Function functionField;
  var untypedField;
  int intField;
}
interface I {
  int intMethod();
}
class SubClass extends ClassWithMethods implements I {}''';

Types types;
MockCompiler compiler;

String returnWithType(String type, expression) {
  return "$type foo() { return $expression; }";
}

Node parseExpression(String text) =>
  parseBodyCode(text, (parser, token) => parser.parseExpression(token));

void setup() {
  compiler = new MockCompiler();
  types = compiler.types;
  intType = compiler.intClass.computeType(compiler);
  doubleType = compiler.doubleClass.computeType(compiler);
  boolType = compiler.boolClass.computeType(compiler);
  stringType = compiler.stringClass.computeType(compiler);
  objectType = compiler.objectClass.computeType(compiler);
}

DartType analyzeType(String text) {
  var node = parseExpression(text);
  TypeCheckerVisitor visitor =
      new TypeCheckerVisitor(compiler, new TreeElementMapping(null), types);
  return visitor.analyze(node);
}

analyzeTopLevel(String text, [expectedWarnings]) {
  if (expectedWarnings == null) expectedWarnings = [];
  if (expectedWarnings is !List) expectedWarnings = [expectedWarnings];

  LibraryElement library = mockLibrary(compiler, text);

  Link<Element> topLevelElements = parseUnit(text, compiler, library);

  for (Link<Element> elements = topLevelElements;
       !elements.isEmpty;
       elements = elements.tail) {
    Node node = elements.head.parseNode(compiler);
    TreeElements mapping = compiler.resolver.resolve(elements.head);
    TypeCheckerVisitor checker =
        new TypeCheckerVisitor(compiler, mapping, types);
    compiler.clearWarnings();
    checker.analyze(node);
    compareWarningKinds(text, expectedWarnings, compiler.warnings);
  }
}

analyze(String text, [expectedWarnings]) {
  if (expectedWarnings == null) expectedWarnings = [];
  if (expectedWarnings is !List) expectedWarnings = [expectedWarnings];

  Token tokens = scan(text);
  NodeListener listener = new NodeListener(compiler, null);
  Parser parser = new Parser(listener);
  parser.parseStatement(tokens);
  Node node = listener.popNode();
  Element function = new ElementX(
      buildSourceString(''), ElementKind.FUNCTION, compiler.mainApp);
  TreeElements elements = compiler.resolveNodeStatement(node, function);
  TypeCheckerVisitor checker = new TypeCheckerVisitor(compiler, elements,
                                                                types);
  compiler.clearWarnings();
  checker.analyze(node);
  compareWarningKinds(text, expectedWarnings, compiler.warnings);
}

analyzeIn(ClassElement classElement, String text, [expectedWarnings]) {
  if (expectedWarnings == null) expectedWarnings = [];
  if (expectedWarnings is !List) expectedWarnings = [expectedWarnings];

  Token tokens = scan(text);
  NodeListener listener = new NodeListener(compiler, null);
  Parser parser = new Parser(listener);
  parser.parseStatement(tokens);
  Node node = listener.popNode();
  classElement.ensureResolved(compiler);
  TreeElements elements = compiler.resolveNodeStatement(node, classElement);
  TypeCheckerVisitor checker = new TypeCheckerVisitor(compiler, elements,
                                                                types);
  compiler.clearWarnings();
  checker.currentClass = classElement;
  checker.analyze(node);
  compareWarningKinds(text, expectedWarnings, compiler.warnings);
}