fix(compiler): update SourceFile with correct file content (#765)

Previously SourceFile.text was the old contents of the file - however the file was during startup. This change updates the SourceFile text so that emit() receives the changed file contents.

Closes #764 

Co-authored-by: Ahn <anhpnnd@gmail.com>

src/__tests__/__snapshots__/ng-jest-compiler.spec.ts.snap

@@ -20,6 +20,50 @@ export { AppComponent };
 //# "
 `;
 
+exports[`NgJestCompiler with isolatedModule false should compile new code when file changes: from hasErrorFileContent 1`] = `
+"\\"use strict\\";
+Object.defineProperty(exports, \\"__esModule\\", { value: true });
+exports.AppComponent = void 0;
+const tslib_1 = require(\\"tslib\\");
+const core_1 = require(\\"@angular/core\\");
+let  = class  {
+    constructor() {
+        this. = ;
+    }
+};
+ = tslib_1.__decorate([
+    core_1.Component({
+        selector: 'app-root',
+        template: require(\\"./app.component.html\\"),
+        styles: []
+    })
+], );
+exports.AppComponent = ;
+//# "
+`;
+
+exports[`NgJestCompiler with isolatedModule false should compile new code when file changes: from noErrorFileContent 1`] = `
+"\\"use strict\\";
+Object.defineProperty(exports, \\"__esModule\\", { value: true });
+exports.AppComponent = void 0;
+const tslib_1 = require(\\"tslib\\");
+const core_1 = require(\\"@angular/core\\");
+let AppComponent = class AppComponent {
+    constructor() {
+        this.title = 'test-app-v10';
+    }
+};
+AppComponent = tslib_1.__decorate([
+    core_1.Component({
+        selector: 'app-root',
+        template: require(\\"./app.component.html\\"),
+        styles: []
+    })
+], AppComponent);
+exports.AppComponent = AppComponent;
+//# "
+`;
+
 exports[`NgJestCompiler with isolatedModule false should throw diagnostics error for new file which is: known by Program 1`] = `"src/__tests__/__mocks__/foo.component.ts(8,3): error TS2322: Type 'string' is not assignable to type 'number'."`;
 
 exports[`NgJestCompiler with isolatedModule false should throw diagnostics error for new file which is: not known by Program 1`] = `"src/__tests__/__mocks__/foo.component.ts(8,3): error TS2322: Type 'string' is not assignable to type 'number'."`;

src/__tests__/ng-jest-compiler.spec.ts

@@ -123,6 +123,24 @@ describe('NgJestCompiler', () => {
       },
     );
 
+    test('should compile new code when file changes', () => {
+      const ngJestConfig = new NgJestConfig(jestCfgStub);
+      const compiler = new NgJestCompiler(ngJestConfig, new Map());
+
+      // Compile the same file with 2 versions of content: noErrorFileContent and hasErrorFileContent
+      const fileName = noErrorFileName;
+      const emittedResult1 = compiler.getCompiledOutput(fileName, noErrorFileContent, true);
+      expect(emittedResult1.substring(0, emittedResult1.indexOf(SOURCE_MAPPING_PREFIX))).toMatchSnapshot(
+        'from noErrorFileContent',
+      );
+      const emittedResult2 = compiler.getCompiledOutput(fileName, hasErrorFileContent, true);
+      expect(emittedResult2.substring(0, emittedResult2.indexOf(SOURCE_MAPPING_PREFIX))).toMatchSnapshot(
+        'from hasErrorFileContent',
+      );
+
+      expect(emittedResult1).not.toEqual(emittedResult2);
+    });
+
     test('should compile codes with useESM true', () => {
       const ngJestConfig = new NgJestConfig({
         ...jestCfgStub,

src/compiler/ng-jest-compiler.ts

@@ -70,20 +70,27 @@ export class NgJestCompiler implements CompilerInstance {
       esModuleInterop,
       module: moduleKind,
     };
+
     if (this._program) {
-      const allDiagnostics: ts.Diagnostic[] = [];
-      if (!this._rootNames.includes(fileName)) {
-        this._logger.debug({ fileName }, 'getCompiledOutput: update memory host, rootFiles and Program');
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      this._tsHost!.updateMemoryHost(fileName, fileContent);
 
+      let sourceFile: ts.SourceFile | undefined;
+      if (!this._rootNames.includes(fileName)) {
+        this._logger.debug({ fileName }, 'getCompiledOutput: adding file to rootNames and updating Program');
         this._rootNames = [...this._rootNames, fileName];
-        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        this._tsHost!.updateMemoryHost(fileName, fileContent);
         this._createOrUpdateProgram();
+        sourceFile = this._program.getSourceFile(fileName);
+      } else {
+        sourceFile = this._program.getSourceFile(fileName);
+        if (sourceFile) {
+          const replaceSpan: ts.TextSpan = { start: 0, length: sourceFile.text.length };
+          sourceFile.update(fileContent, { span: replaceSpan, newLength: fileContent.length });
+        }
       }
 
       this._logger.debug({ fileName }, 'getCompiledOutput: compiling using Program');
 
-      const sourceFile = this._program.getSourceFile(fileName);
       const emitResult = this._program.emit(sourceFile, undefined, undefined, undefined, {
         ...customTransformers,
         before: [
@@ -98,8 +105,10 @@ export class NgJestCompiler implements CompilerInstance {
           replaceResources(this.isAppPath, this._program.getTypeChecker),
         ],
       });
+
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       const compiledOutput: [string, string] = this._tsHost!.getEmittedResult();
+      const allDiagnostics: ts.Diagnostic[] = [];
       if (this.ngJestConfig.shouldReportDiagnostics(fileName)) {
         this._logger.debug({ fileName }, 'getCompiledOutput: getting diagnostics');