feat: add typescript file extension support (#32)

src/__tests__/fixtures/fixtures/typescript/code.ts

@@ -0,0 +1 @@
+'use strict';

src/__tests__/index.js

@@ -257,11 +257,12 @@ test('can pass tests in fixtures relative to the filename', async () => {
     }),
   )
   expect(describeSpy).toHaveBeenCalledTimes(2)
-  expect(itSpy).toHaveBeenCalledTimes(5)
+  expect(itSpy).toHaveBeenCalledTimes(6)
   expect(itSpy.mock.calls).toEqual([
     [`changed`, expect.any(Function)],
     [`nested a`, expect.any(Function)],
     [`nested b`, expect.any(Function)],
+    [`typescript`, expect.any(Function)],
     [`unchanged`, expect.any(Function)],
     [`without output file`, expect.any(Function)],
   ])
@@ -291,7 +292,7 @@ test('creates output file for new tests', async () => {
   )
 
   expect(writeFileSyncSpy.mock.calls[0]).toEqual([
-    expect.stringMatching(/\/output\.js$/),
+    expect.stringMatching(/\/output\.(j|t)s$/),
     "'use strict';",
   ])
 })

src/index.js

@@ -209,16 +209,21 @@ function pluginTester({
 const createFixtureTests = (fixturesDir, options) => {
   fs.readdirSync(fixturesDir).forEach(caseName => {
     const fixtureDir = path.join(fixturesDir, caseName)
-    const codePath = path.join(fixtureDir, 'code.js')
+    const jsCodePath = path.join(fixtureDir, 'code.js')
+    const tsCodePath = path.join(fixtureDir, 'code.ts')
     const blockTitle = caseName.split('-').join(' ')
+    const codePath =
+      (pathExists.sync(jsCodePath) && jsCodePath) ||
+      (pathExists.sync(tsCodePath) && tsCodePath)
 
-    if (!pathExists.sync(codePath)) {
+    if (!codePath) {
       describe(blockTitle, () => {
         createFixtureTests(fixtureDir, options)
       })
       return
     }
 
+    const ext = /\.ts$/.test(codePath) ? '.ts' : '.js'
     it(blockTitle, () => {
       const {plugin, pluginOptions, fixtureOutputName, babel, ...rest} = options
 
@@ -239,7 +244,7 @@ const createFixtureTests = (fixturesDir, options) => {
       )
       const actual = babel.transformFileSync(codePath, babelOptions).code.trim()
 
-      const outputPath = path.join(fixtureDir, `${fixtureOutputName}.js`)
+      const outputPath = path.join(fixtureDir, `${fixtureOutputName}${ext}`)
 
       if (!fs.existsSync(outputPath)) {
         fs.writeFileSync(outputPath, actual)
@@ -251,7 +256,7 @@ const createFixtureTests = (fixturesDir, options) => {
       assert.equal(
         actual,
         output,
-        `actual output does not match ${fixtureOutputName}.js`,
+        `actual output does not match ${fixtureOutputName}${ext}`,
       )
     })
   })