angular-docs-cn/packages/compiler-cli/linker/test/file_linker/file_linker_spec.ts

/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import * as o from '@angular/compiler/src/output/output_ast';
import * as ts from 'typescript';

import {TypeScriptAstFactory} from '../../../src/ngtsc/translator';
import {AstHost} from '../../src/ast/ast_host';
import {TypeScriptAstHost} from '../../src/ast/typescript/typescript_ast_host';
import {DeclarationScope} from '../../src/file_linker/declaration_scope';
import {FileLinker} from '../../src/file_linker/file_linker';
import {LinkerEnvironment} from '../../src/file_linker/linker_environment';
import {DEFAULT_LINKER_OPTIONS} from '../../src/file_linker/linker_options';
import {PartialDirectiveLinkerVersion1} from '../../src/file_linker/partial_linkers/partial_directive_linker_1';
import {generate} from './helpers';

describe('FileLinker', () => {
  let factory: TypeScriptAstFactory;
  beforeEach(() => factory = new TypeScriptAstFactory());

  describe('isPartialDeclaration()', () => {
    it('should return true if the callee is recognized', () => {
      const {fileLinker} = createFileLinker();
      expect(fileLinker.isPartialDeclaration('$ngDeclareDirective')).toBe(true);
      expect(fileLinker.isPartialDeclaration('$ngDeclareComponent')).toBe(true);
    });

    it('should return false if the callee is not recognized', () => {
      const {fileLinker} = createFileLinker();
      expect(fileLinker.isPartialDeclaration('$foo')).toBe(false);
    });
  });

  describe('linkPartialDeclaration()', () => {
    it('should throw an error if the function name is not recognised', () => {
      const {fileLinker} = createFileLinker();
      const version = factory.createLiteral(1);
      const ngImport = factory.createIdentifier('core');
      const declarationArg = factory.createObjectLiteral([
        {propertyName: 'version', quoted: false, value: version},
        {propertyName: 'ngImport', quoted: false, value: ngImport},
      ]);
      expect(
          () => fileLinker.linkPartialDeclaration(
              'foo', [declarationArg], new MockDeclarationScope()))
          .toThrowError('Unknown partial declaration function foo.');
    });

    it('should throw an error if the metadata object does not have a `version` property', () => {
      const {fileLinker} = createFileLinker();
      const ngImport = factory.createIdentifier('core');
      const declarationArg = factory.createObjectLiteral([
        {propertyName: 'ngImport', quoted: false, value: ngImport},
      ]);
      expect(
          () => fileLinker.linkPartialDeclaration(
              '$ngDeclareDirective', [declarationArg], new MockDeclarationScope()))
          .toThrowError(`Expected property 'version' to be present.`);
    });

    it('should throw an error if the metadata object does not have a `ngImport` property', () => {
      const {fileLinker} = createFileLinker();
      const ngImport = factory.createIdentifier('core');
      const declarationArg = factory.createObjectLiteral([
        {propertyName: 'version', quoted: false, value: ngImport},
      ]);
      expect(
          () => fileLinker.linkPartialDeclaration(
              '$ngDeclareDirective', [declarationArg], new MockDeclarationScope()))
          .toThrowError(`Expected property 'ngImport' to be present.`);
    });

    it('should call `linkPartialDeclaration()` on the appropriate partial compiler', () => {
      const {fileLinker} = createFileLinker();
      const compileSpy = spyOn(PartialDirectiveLinkerVersion1.prototype, 'linkPartialDeclaration')
                             .and.returnValue(o.literal('compilation result'));

      const ngImport = factory.createIdentifier('core');
      const version = factory.createLiteral(1);
      const declarationArg = factory.createObjectLiteral([
        {propertyName: 'ngImport', quoted: false, value: ngImport},
        {propertyName: 'version', quoted: false, value: version},
      ]);

      const compilationResult = fileLinker.linkPartialDeclaration(
          '$ngDeclareDirective', [declarationArg], new MockDeclarationScope());

      expect(compilationResult).toEqual(factory.createLiteral('compilation result'));
      expect(compileSpy).toHaveBeenCalled();
      expect(compileSpy.calls.mostRecent().args[3].getNode('ngImport')).toBe(ngImport);
    });
  });

  describe('getConstantStatements()', () => {
    it('should capture shared constant values', () => {
      const {fileLinker} = createFileLinker();
      spyOnLinkPartialDeclarationWithConstants(o.literal('REPLACEMENT'));

      // Here we use the `core` idenfifier for `ngImport` to trigger the use of a shared scope for
      // constant statements.
      const declarationArg = factory.createObjectLiteral([
        {propertyName: 'ngImport', quoted: false, value: factory.createIdentifier('core')},
        {propertyName: 'version', quoted: false, value: factory.createLiteral(1)},
      ]);

      const replacement = fileLinker.linkPartialDeclaration(
          '$ngDeclareDirective', [declarationArg], new MockDeclarationScope());
      expect(generate(replacement)).toEqual('"REPLACEMENT"');

      const results = fileLinker.getConstantStatements();
      expect(results.length).toEqual(1);
      const {constantScope, statements} = results[0];
      expect(constantScope).toBe(MockConstantScopeRef.singleton);
      expect(statements.map(generate)).toEqual(['const _c0 = [1];']);
    });

    it('should be no shared constant statements to capture when they are emitted into the replacement IIFE',
       () => {
         const {fileLinker} = createFileLinker();
         spyOnLinkPartialDeclarationWithConstants(o.literal('REPLACEMENT'));

         // Here we use a string literal `"not-a-module"` for `ngImport` to cause constant
         // statements to be emitted in an IIFE rather than added to the shared constant scope.
         const declarationArg = factory.createObjectLiteral([
           {propertyName: 'ngImport', quoted: false, value: factory.createLiteral('not-a-module')},
           {propertyName: 'version', quoted: false, value: factory.createLiteral(1)},
         ]);

         const replacement = fileLinker.linkPartialDeclaration(
             '$ngDeclareDirective', [declarationArg], new MockDeclarationScope());
         expect(generate(replacement))
             .toEqual('function () { const _c0 = [1]; return "REPLACEMENT"; }()');

         const results = fileLinker.getConstantStatements();
         expect(results.length).toEqual(0);
       });
  });

  function createFileLinker(): {
    host: AstHost<ts.Expression>,
    fileLinker: FileLinker<MockConstantScopeRef, ts.Statement, ts.Expression>
  } {
    const linkerEnvironment = LinkerEnvironment.create<ts.Statement, ts.Expression>(
        new TypeScriptAstHost(), new TypeScriptAstFactory(), DEFAULT_LINKER_OPTIONS);
    const fileLinker = new FileLinker<MockConstantScopeRef, ts.Statement, ts.Expression>(
        linkerEnvironment, 'test.js', '// test code');
    return {host: linkerEnvironment.host, fileLinker};
  }
});


/**
 * This mock implementation of `DeclarationScope` will return a singleton instance of
 * `MockConstantScopeRef` if the expression is an identifier, or `null` otherwise.
 *
 * This way we can simulate whether the constants will be shared or inlined into an IIFE.
 */
class MockDeclarationScope implements DeclarationScope<MockConstantScopeRef, ts.Expression> {
  getConstantScopeRef(expression: ts.Expression): MockConstantScopeRef|null {
    if (ts.isIdentifier(expression)) {
      return MockConstantScopeRef.singleton;
    } else {
      return null;
    }
  }
}

class MockConstantScopeRef {
  private constructor() {}
  static singleton = new MockDeclarationScope();
}

/**
 * Spy on the `PartialDirectiveLinkerVersion1.linkPartialDeclaration()` method, triggering
 * shared constants to be created.
 */
function spyOnLinkPartialDeclarationWithConstants(replacement: o.Expression) {
  let callCount = 0;
  spyOn(PartialDirectiveLinkerVersion1.prototype, 'linkPartialDeclaration')
      .and.callFake(((sourceUrl, code, constantPool) => {
                      const constArray = o.literalArr([o.literal(++callCount)]);
                      // We have to add the constant twice or it will not create a shared statement
                      constantPool.getConstLiteral(constArray);
                      constantPool.getConstLiteral(constArray);
                      return replacement;
                    }) as typeof PartialDirectiveLinkerVersion1.prototype.linkPartialDeclaration);
}