fix(compiler): return file content on emitSkipped for non ts/tsx files

src/compiler/ts-compiler.spec.ts

@@ -195,7 +195,7 @@ describe('TsCompiler', () => {
         expect(output).toEqual(updateOutput(jsOutput, fileName, sourceMap))
       })
 
-      test('should return original file content if emitSkipped is true', () => {
+      test('should show a warning message and return original file content for non ts/tsx files if emitSkipped is true', () => {
         const compiler = makeCompiler({
           tsJestConfig: { ...baseTsJestConfig },
         })
@@ -205,16 +205,50 @@ describe('TsCompiler', () => {
           emitSkipped: true,
         } as EmitOutput)
         // @ts-expect-error testing purpose
+        compiler._logger.warn = jest.fn()
+        // @ts-expect-error testing purpose
         compiler._doTypeChecking = jest.fn()
-        const output = compiler.getCompiledOutput(fileContent, fileName, {
+        const fileToCheck = fileName.replace('.ts', '.js')
+
+        const output = compiler.getCompiledOutput(fileContent, fileToCheck, {
           depGraphs: new Map(),
           supportsStaticESM: false,
           watchMode: false,
         })
 
-        expect(output).toEqual(updateOutput(fileContent, fileName, sourceMap))
+        // @ts-expect-error testing purpose
+        expect(compiler._logger.warn).toHaveBeenCalled()
+        expect(output).toEqual(updateOutput(fileContent, fileToCheck, sourceMap))
       })
 
+      test.each([fileName, fileName.replace('.ts', '.tsx')])(
+        'should throw error for ts/tsx files if emitSkipped is true',
+        (fileToCheck) => {
+          const compiler = makeCompiler({
+            tsJestConfig: { ...baseTsJestConfig },
+          })
+          // @ts-expect-error testing purpose
+          compiler._languageService.getEmitOutput = jest.fn().mockReturnValueOnce({
+            outputFiles: [{ text: sourceMap }, { text: jsOutput }],
+            emitSkipped: true,
+          } as EmitOutput)
+          // @ts-expect-error testing purpose
+          compiler._logger.warn = jest.fn()
+          // @ts-expect-error testing purpose
+          compiler._doTypeChecking = jest.fn()
+
+          // @ts-expect-error testing purpose
+          expect(compiler._logger.warn).not.toHaveBeenCalled()
+          expect(() =>
+            compiler.getCompiledOutput(fileContent, fileToCheck, {
+              depGraphs: new Map(),
+              supportsStaticESM: false,
+              watchMode: false,
+            }),
+          ).toThrowError()
+        },
+      )
+
       test('should throw error when there are no outputFiles', () => {
         const compiler = makeCompiler({
           tsJestConfig: { ...baseTsJestConfig },

src/compiler/ts-compiler.ts

@@ -176,9 +176,13 @@ export class TsCompiler implements TsCompilerInstance {
       const output: EmitOutput = this._languageService.getEmitOutput(fileName)
       this._doTypeChecking(fileName, options.depGraphs, options.watchMode)
       if (output.emitSkipped) {
-        this._logger.warn(interpolate(Errors.CannotProcessFile, { file: fileName }))
+        if (TS_TSX_REGEX.test(fileName)) {
+          throw new Error(interpolate(Errors.CannotProcessFile, { file: fileName }))
+        } else {
+          this._logger.warn(interpolate(Errors.CannotProcessFileReturnOriginal, { file: fileName }))
 
-        return updateOutput(fileContent, fileName, '{}')
+          return updateOutput(fileContent, fileName, '{}')
+        }
       }
       // Throw an error when requiring `.d.ts` files.
       if (!output.outputFiles.length) {

src/utils/messages.ts

@@ -17,7 +17,8 @@ export const enum Errors {
   GotUnknownFileTypeWithBabel = 'Got a unknown file type to compile (file: {{path}}). To fix this, in your Jest config change the `transform` key which value is `ts-jest` so that it does not match this kind of files anymore. If you still want Babel to process it, add another entry to the `transform` option with value `babel-jest` which key matches this type of files.',
   ConfigNoModuleInterop = 'If you have issues related to imports, you should consider setting `esModuleInterop` to `true` in your TypeScript configuration file (usually `tsconfig.json`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.',
   MismatchNodeTargetMapping = 'There is a mismatch between your NodeJs version {{nodeJsVer}} and your TypeScript target {{compilationTarget}}. This might lead to some unexpected errors when running tests with `ts-jest`. To fix this, you can check https://github.com/microsoft/TypeScript/wiki/Node-Target-Mapping',
-  CannotProcessFile = "Unable to process '{{file}}', falling back to original file content. Please make sure that `outDir` in your tsconfig is neither `''` or `'.'`. You can also configure Jest config option `transformIgnorePatterns` to ignore {{file}} from transformation",
+  CannotProcessFileReturnOriginal = "Unable to process '{{file}}', falling back to original file content. You can also configure Jest config option `transformIgnorePatterns` to ignore {{file}} from transformation or make sure that `outDir` in your tsconfig is neither `''` or `'.'`",
+  CannotProcessFile = "Unable to process '{{file}}', please make sure that `outDir` in your tsconfig is neither `''` or `'.'`. You can also configure Jest config option `transformIgnorePatterns` to inform `ts-jest` to transform {{file}}",
 }
 
 /**