feat(formatResult): add formatResult option (#17)

README.md

@@ -248,6 +248,12 @@ If you set up some state, it's quite possible you want to tear it down. You can
 either define this as its own property, or you can return it from the `setup`
 function. This can likewise return a promise if it's asynchronous.
 
+#### formatResult
+
+This is a function and if it's specified, it allows you to format the result
+however you like. The use case for this originally was for testing codemods
+and formatting their result with `prettier-eslint`.
+
 ## Examples
 
 ### Full Example + Docs

src/__tests__/index.js

@@ -514,6 +514,17 @@ test('error logged and thrown if teardown throws', async () => {
   )
 })
 
+test('allows formatting the result', async () => {
+  const formatResultSpy = jest.fn(r => r)
+  await pluginTester(
+    getOptions({
+      tests: [{code: simpleTest, formatResult: formatResultSpy}],
+    }),
+  )
+  expect(formatResultSpy).toHaveBeenCalledTimes(1)
+  expect(formatResultSpy).toHaveBeenCalledWith(simpleTest)
+})
+
 function getOptions(overrides) {
   return {
     pluginName: 'captains-log',

src/index.js

@@ -65,6 +65,7 @@ function pluginTester(
         error,
         setup = noop,
         teardown,
+        formatResult = r => r,
       } = merge(
         {},
         testerConfig,
@@ -141,7 +142,9 @@ function pluginTester(
         let errored = false
 
         try {
-          result = babel.transform(code, babelOptions).code.trim()
+          result = formatResult(
+            babel.transform(code, babelOptions).code.trim(),
+          )
         } catch (err) {
           if (error) {
             errored = true