In ES5 code, TypeScript requires certain helpers (such as
`__spreadArrays()`) to be able to support ES2015+ features. These
helpers can be either imported from `tslib` (by setting the
`importHelpers` TS compiler option to `true`) or emitted inline (by
setting the `importHelpers` and `noEmitHelpers` TS compiler options to
`false`, which is the default value for both).
Ngtsc's `StaticInterpreter` (which is also used during ngcc processing)
is able to statically evaluate some of these helpers (currently
`__assign()`, `__spread()` and `__spreadArrays()`), as long as
`ReflectionHost#getDefinitionOfFunction()` correctly detects the
declaration of the helper. For this to happen, the left-hand side of the
corresponding call expression (i.e. `__spread(...)` or
`tslib.__spread(...)`) must be evaluated as a function declaration for
`getDefinitionOfFunction()` to be called with.
In the case of imported helpers, the `tslib.__someHelper` expression was
resolved to a function declaration of the form
`export declare function __someHelper(...args: any[][]): any[];`, which
allows `getDefinitionOfFunction()` to correctly map it to a TS helper.
In contrast, in the case of emitted helpers (and regardless of the
module format: `CommonJS`, `ESNext`, `UMD`, etc.)), the `__someHelper`
identifier was resolved to a variable declaration of the form
`var __someHelper = (this && this.__someHelper) || function () { ... }`,
which upon further evaluation was categorized as a `DynamicValue`
(prohibiting further evaluation by the `getDefinitionOfFunction()`).
As a result of the above, emitted TypeScript helpers were not evaluated
in ES5 code.
---
This commit changes the detection of TS helpers to leverage the existing
`KnownFn` feature (previously only used for built-in functions).
`Esm5ReflectionHost` is changed to always return `KnownDeclaration`s for
TS helpers, both imported (`getExportsOfModule()`) as well as emitted
(`getDeclarationOfIdentifier()`).
Similar changes are made to `CommonJsReflectionHost` and
`UmdReflectionHost`.
The `KnownDeclaration`s are then mapped to `KnownFn`s in
`StaticInterpreter`, allowing it to statically evaluate call expressions
involving any kind of TS helpers.
Jira issue: https://angular-team.atlassian.net/browse/FW-1689
PR Close #35191
		
	
			
		
			
				
	
	
		
			210 lines
		
	
	
		
			8.3 KiB
		
	
	
	
		
			TypeScript
		
	
	
	
	
	
			
		
		
	
	
			210 lines
		
	
	
		
			8.3 KiB
		
	
	
	
		
			TypeScript
		
	
	
	
	
	
| /**
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|  * @license
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|  * Copyright Google Inc. All Rights Reserved.
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|  *
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|  * Use of this source code is governed by an MIT-style license that can be
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|  * found in the LICENSE file at https://angular.io/license
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|  */
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| 
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| import * as ts from 'typescript';
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| import {KnownDeclaration} from '../../src/ngtsc/reflection';
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| import {FactoryMap, getTsHelperFnFromDeclaration, getTsHelperFnFromIdentifier, isRelativePath, stripExtension} from '../src/utils';
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| 
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| describe('FactoryMap', () => {
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|   it('should return an existing value', () => {
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|     const factoryFnSpy = jasmine.createSpy('factory');
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|     const factoryMap = new FactoryMap<string, string>(factoryFnSpy, [['k1', 'v1'], ['k2', 'v2']]);
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| 
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|     expect(factoryMap.get('k1')).toBe('v1');
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|     expect(factoryMap.get('k2')).toBe('v2');
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|     expect(factoryFnSpy).not.toHaveBeenCalled();
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|   });
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| 
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|   it('should not treat falsy values as missing', () => {
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|     const factoryFnSpy = jasmine.createSpy('factory').and.returnValue('never gonna happen');
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|     const factoryMap = new FactoryMap<string, any>(factoryFnSpy, [
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|       ['k1', ''],
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|       ['k2', 0],
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|       ['k3', false],
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|       ['k4', null],
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|       ['k5', undefined],
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|     ]);
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| 
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|     expect(factoryMap.get('k1')).toBe('');
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|     expect(factoryMap.get('k2')).toBe(0);
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|     expect(factoryMap.get('k3')).toBe(false);
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|     expect(factoryMap.get('k4')).toBe(null);
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|     expect(factoryMap.get('k5')).toBe(undefined);
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|     expect(factoryFnSpy).not.toHaveBeenCalled();
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|   });
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| 
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|   it('should create, store and return the value if it does not exist', () => {
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|     const factoryFnSpy = jasmine.createSpy('factory').and.returnValues('v3', 'never gonna happen');
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|     const factoryMap = new FactoryMap(factoryFnSpy, [['k1', 'v1'], ['k2', 'v2']]);
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| 
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|     expect(factoryMap.get('k3')).toBe('v3');
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|     expect(factoryFnSpy).toHaveBeenCalledTimes(1);
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| 
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|     factoryFnSpy.calls.reset();
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| 
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|     expect(factoryMap.get('k3')).toBe('v3');
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|     expect(factoryFnSpy).not.toHaveBeenCalled();
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|   });
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| });
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| 
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| describe('getTsHelperFnFromDeclaration()', () => {
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|   const createFunctionDeclaration = (fnName?: string) => ts.createFunctionDeclaration(
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|       undefined, undefined, undefined, fnName, undefined, [], undefined, undefined);
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|   const createVariableDeclaration = (varName: string) =>
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|       ts.createVariableDeclaration(varName, undefined, undefined);
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| 
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|   it('should recognize the `__assign` helper as function declaration', () => {
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|     const decl1 = createFunctionDeclaration('__assign');
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|     const decl2 = createFunctionDeclaration('__assign$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(KnownDeclaration.TsHelperAssign);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(KnownDeclaration.TsHelperAssign);
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|   });
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| 
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|   it('should recognize the `__assign` helper as variable declaration', () => {
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|     const decl1 = createVariableDeclaration('__assign');
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|     const decl2 = createVariableDeclaration('__assign$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(KnownDeclaration.TsHelperAssign);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(KnownDeclaration.TsHelperAssign);
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|   });
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| 
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|   it('should recognize the `__spread` helper as function declaration', () => {
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|     const decl1 = createFunctionDeclaration('__spread');
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|     const decl2 = createFunctionDeclaration('__spread$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(KnownDeclaration.TsHelperSpread);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(KnownDeclaration.TsHelperSpread);
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|   });
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| 
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|   it('should recognize the `__spread` helper as variable declaration', () => {
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|     const decl1 = createVariableDeclaration('__spread');
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|     const decl2 = createVariableDeclaration('__spread$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(KnownDeclaration.TsHelperSpread);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(KnownDeclaration.TsHelperSpread);
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|   });
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| 
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|   it('should recognize the `__spreadArrays` helper as function declaration', () => {
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|     const decl1 = createFunctionDeclaration('__spreadArrays');
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|     const decl2 = createFunctionDeclaration('__spreadArrays$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(KnownDeclaration.TsHelperSpreadArrays);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(KnownDeclaration.TsHelperSpreadArrays);
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|   });
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| 
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|   it('should recognize the `__spreadArrays` helper as variable declaration', () => {
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|     const decl1 = createVariableDeclaration('__spreadArrays');
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|     const decl2 = createVariableDeclaration('__spreadArrays$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(KnownDeclaration.TsHelperSpreadArrays);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(KnownDeclaration.TsHelperSpreadArrays);
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|   });
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| 
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|   it('should return null for unrecognized helpers', () => {
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|     const decl1 = createFunctionDeclaration('__foo');
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|     const decl2 = createVariableDeclaration('spread');
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|     const decl3 = createFunctionDeclaration('spread$42');
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| 
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|     expect(getTsHelperFnFromDeclaration(decl1)).toBe(null);
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|     expect(getTsHelperFnFromDeclaration(decl2)).toBe(null);
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|     expect(getTsHelperFnFromDeclaration(decl3)).toBe(null);
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|   });
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| 
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|   it('should return null for unnamed declarations', () => {
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|     const unnamledDecl = createFunctionDeclaration(undefined);
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| 
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|     expect(getTsHelperFnFromDeclaration(unnamledDecl)).toBe(null);
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|   });
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| 
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|   it('should return null for non-function/variable declarations', () => {
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|     const classDecl =
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|         ts.createClassDeclaration(undefined, undefined, '__assign', undefined, undefined, []);
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| 
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|     expect(classDecl.name !.text).toBe('__assign');
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|     expect(getTsHelperFnFromDeclaration(classDecl)).toBe(null);
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|   });
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| });
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| 
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| describe('getTsHelperFnFromIdentifier()', () => {
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|   it('should recognize the `__assign` helper', () => {
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|     const id1 = ts.createIdentifier('__assign');
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|     const id2 = ts.createIdentifier('__assign$42');
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| 
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|     expect(getTsHelperFnFromIdentifier(id1)).toBe(KnownDeclaration.TsHelperAssign);
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|     expect(getTsHelperFnFromIdentifier(id2)).toBe(KnownDeclaration.TsHelperAssign);
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|   });
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| 
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|   it('should recognize the `__spread` helper', () => {
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|     const id1 = ts.createIdentifier('__spread');
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|     const id2 = ts.createIdentifier('__spread$42');
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| 
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|     expect(getTsHelperFnFromIdentifier(id1)).toBe(KnownDeclaration.TsHelperSpread);
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|     expect(getTsHelperFnFromIdentifier(id2)).toBe(KnownDeclaration.TsHelperSpread);
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|   });
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| 
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|   it('should recognize the `__spreadArrays` helper', () => {
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|     const id1 = ts.createIdentifier('__spreadArrays');
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|     const id2 = ts.createIdentifier('__spreadArrays$42');
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| 
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|     expect(getTsHelperFnFromIdentifier(id1)).toBe(KnownDeclaration.TsHelperSpreadArrays);
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|     expect(getTsHelperFnFromIdentifier(id2)).toBe(KnownDeclaration.TsHelperSpreadArrays);
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|   });
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| 
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|   it('should return null for unrecognized helpers', () => {
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|     const id1 = ts.createIdentifier('__foo');
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|     const id2 = ts.createIdentifier('spread');
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|     const id3 = ts.createIdentifier('spread$42');
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| 
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|     expect(getTsHelperFnFromIdentifier(id1)).toBe(null);
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|     expect(getTsHelperFnFromIdentifier(id2)).toBe(null);
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|     expect(getTsHelperFnFromIdentifier(id3)).toBe(null);
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|   });
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| });
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| 
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| describe('isRelativePath()', () => {
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|   it('should return true for relative paths', () => {
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|     expect(isRelativePath('.')).toBe(true);
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|     expect(isRelativePath('..')).toBe(true);
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|     expect(isRelativePath('./')).toBe(true);
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|     expect(isRelativePath('../')).toBe(true);
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|     expect(isRelativePath('./abc/xyz')).toBe(true);
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|     expect(isRelativePath('../abc/xyz')).toBe(true);
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|   });
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| 
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|   it('should return true for absolute paths', () => {
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|     expect(isRelativePath('/')).toBe(true);
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|     expect(isRelativePath('/abc/xyz')).toBe(true);
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|   });
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| 
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|   it('should return false for other paths', () => {
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|     expect(isRelativePath('abc')).toBe(false);
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|     expect(isRelativePath('abc/xyz')).toBe(false);
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|     expect(isRelativePath('.abc')).toBe(false);
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|     expect(isRelativePath('..abc')).toBe(false);
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|     expect(isRelativePath('@abc')).toBe(false);
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|     expect(isRelativePath('.abc/xyz')).toBe(false);
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|     expect(isRelativePath('..abc/xyz')).toBe(false);
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|     expect(isRelativePath('@abc/xyz')).toBe(false);
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|   });
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| });
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| 
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| describe('stripExtension()', () => {
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|   it('should strip the extension from a file name', () => {
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|     expect(stripExtension('foo.ts')).toBe('foo');
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|     expect(stripExtension('/foo/bar.ts')).toBe('/foo/bar');
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|     expect(stripExtension('/foo/bar.d.ts')).toBe('/foo/bar');
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|   });
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| 
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|   it('should do nothing if there is no extension in a file name', () => {
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|     expect(stripExtension('foo')).toBe('foo');
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|     expect(stripExtension('/foo/bar')).toBe('/foo/bar');
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|     expect(stripExtension('/fo-o/b_ar')).toBe('/fo-o/b_ar');
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|   });
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| });
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