fix(compile): js files were never transpiled thru TS

Closes #740

Author: huafu

src/ts-jest-transformer.spec.ts

@@ -64,7 +64,7 @@ describe('process', () => {
     typescript = { options: {} } as any
   })
 
-  it('should process input without babel', () => {
+  it('should process ts input without babel', () => {
     expect(process()).toBe(`ts:${INPUT}`)
     expect(config.shouldStringifyContent.mock.calls).toMatchInlineSnapshot(`
 Array [
@@ -83,7 +83,28 @@ Array [
 `)
   })
 
-  it('should process input with babel', () => {
+  it('should process js input without babel', () => {
+    typescript.options.allowJs = true
+    args[1] = '/foo/bar.js'
+    expect(process()).toBe(`ts:${INPUT}`)
+    expect(config.shouldStringifyContent.mock.calls).toMatchInlineSnapshot(`
+Array [
+  Array [
+    "/foo/bar.js",
+  ],
+]
+`)
+    expect(config.tsCompiler.compile.mock.calls).toMatchInlineSnapshot(`
+Array [
+  Array [
+    "export default \\"foo\\"",
+    "/foo/bar.js",
+  ],
+]
+`)
+  })
+
+  it('should process ts input with babel', () => {
     babel = { process: jest.fn(s => `babel:${s}`) }
     expect(process()).toBe(`babel:ts:${INPUT}`)
     expect(config.shouldStringifyContent.mock.calls).toMatchInlineSnapshot(`
@@ -115,6 +136,40 @@ Array [
 `)
   })
 
+  it('should process js input with babel', () => {
+    typescript.options.allowJs = true
+    babel = { process: jest.fn(s => `babel:${s}`) }
+    args[1] = '/foo/bar.js'
+    expect(process()).toBe(`babel:ts:${INPUT}`)
+    expect(config.shouldStringifyContent.mock.calls).toMatchInlineSnapshot(`
+Array [
+  Array [
+    "/foo/bar.js",
+  ],
+]
+`)
+    expect(config.babelJestTransformer.process.mock.calls).toMatchInlineSnapshot(`
+Array [
+  Array [
+    "ts:export default \\"foo\\"",
+    "/foo/bar.js",
+    Object {},
+    Object {
+      "instrument": false,
+    },
+  ],
+]
+`)
+    expect(config.tsCompiler.compile.mock.calls).toMatchInlineSnapshot(`
+Array [
+  Array [
+    "export default \\"foo\\"",
+    "/foo/bar.js",
+  ],
+]
+`)
+  })
+
   it('should return stringified version of file', () => {
     config.shouldStringifyContent.mockImplementation(() => true)
     expect(process()).toMatchInlineSnapshot(`"module.exports=\\"export default \\\\\\"foo\\\\\\"\\""`)

src/ts-jest-transformer.ts

@@ -111,7 +111,7 @@ export class TsJestTransformer implements jest.Transformer {
       // we've got a '.js' but the compiler option `allowJs` is not set or set to false
       this.logger.warn({ fileName: filePath }, interpolate(Errors.GotJsFileButAllowJsFalse, { path: filePath }))
       result = source
-    } else if (isTsFile) {
+    } else if (isJsFile || isTsFile) {
       // transpile TS code (source maps are included)
       result = configs.tsCompiler.compile(source, filePath)
     } else {