test(compiler-cli): add integration test for relative rootDir (#41359)

this will make it easier to detect regressions of the relative rootDir behavior

PR Close #41359

packages/compiler-cli/test/ngtsc/env.ts

@@ -30,6 +30,7 @@ export class NgtscTestEnvironment {
   private multiCompileHostExt: MultiCompileHostExt|null = null;
   private oldProgram: Program|null = null;
   private changedResources: Set<string>|null = null;
+  private commandLineArgs = ['-p', this.basePath];
 
   private constructor(
       private fs: FileSystem, readonly outDir: AbsoluteFsPath, readonly basePath: AbsoluteFsPath) {}
@@ -114,6 +115,10 @@ export class NgtscTestEnvironment {
     setWrapHostForTest(makeWrapHost(new ResourceLoadingCompileHost(this.fs)));
   }
 
+  addCommandLineArgs(...args: string[]): void {
+    this.commandLineArgs.push(...args);
+  }
+
   flushWrittenFileTracking(): void {
     if (this.multiCompileHostExt === null) {
       throw new Error(`Not tracking written files - call enableMultipleCompilations()`);
@@ -214,7 +219,7 @@ export class NgtscTestEnvironment {
       };
     }
     const exitCode = main(
-        ['-p', this.basePath], errorSpy, undefined, customTransformers, reuseProgram,
+        this.commandLineArgs, errorSpy, undefined, customTransformers, reuseProgram,
         this.changedResources);
     expect(errorSpy).not.toHaveBeenCalled();
     expect(exitCode).toBe(0);
@@ -236,7 +241,7 @@ export class NgtscTestEnvironment {
     }
 
     const diags = mainDiagnosticsForTest(
-        ['-p', this.basePath], undefined, reuseProgram, this.changedResources);
+        this.commandLineArgs, undefined, reuseProgram, this.changedResources);
 
 
     if (this.multiCompileHostExt !== null) {
@@ -248,7 +253,7 @@ export class NgtscTestEnvironment {
   }
 
   async driveDiagnosticsAsync(): Promise<ReadonlyArray<ts.Diagnostic>> {
-    const {rootNames, options} = readNgcCommandLineAndConfiguration(['-p', this.basePath]);
+    const {rootNames, options} = readNgcCommandLineAndConfiguration(this.commandLineArgs);
     const host = createCompilerHost({options});
     const program = createProgram({rootNames, host, options});
     await program.loadNgStructureAsync();
@@ -258,14 +263,14 @@ export class NgtscTestEnvironment {
   }
 
   driveRoutes(entryPoint?: string): LazyRoute[] {
-    const {rootNames, options} = readNgcCommandLineAndConfiguration(['-p', this.basePath]);
+    const {rootNames, options} = readNgcCommandLineAndConfiguration(this.commandLineArgs);
     const host = createCompilerHost({options});
     const program = createProgram({rootNames, host, options});
     return program.listLazyRoutes(entryPoint);
   }
 
   driveIndexer(): Map<DeclarationNode, IndexedComponent> {
-    const {rootNames, options} = readNgcCommandLineAndConfiguration(['-p', this.basePath]);
+    const {rootNames, options} = readNgcCommandLineAndConfiguration(this.commandLineArgs);
     const host = createCompilerHost({options});
     const program = createProgram({rootNames, host, options});
     return (program as NgtscProgram).getIndexedComponents();

packages/compiler-cli/test/ngtsc/ngtsc_spec.ts

@@ -54,6 +54,25 @@ function allTests(os: string) {
       env.tsconfig();
     });
 
+    it('should accept relative file paths as command line argument', () => {
+      env.addCommandLineArgs('--rootDir', './rootDir');
+      env.write('rootDir/test.html', '<p>Hello World</p>');
+      env.write('rootDir/test.ts', `
+        import {Component} from '@angular/core';
+
+        @Component({
+          selector: 'test-cmp',
+          templateUrl: 'test.html',
+        })
+        export class TestCmp {}
+    `);
+
+      env.driveMain();
+
+      const jsContents = env.getContents('test.js');
+      expect(jsContents).toContain('Hello World');
+    });
+
     it('should compile Injectables without errors', () => {
       env.write('test.ts', `
         import {Injectable} from '@angular/core';