feat: automatically whitelist Marko dependencies in transforms

BREAKING CHANGE: Preset now contains more options.
BREAKING CHANGE: Preset contains babel-jest by default (same as vanilla jest).

README.md

@@ -133,17 +133,14 @@ In the above example config, any tests with `*.browser.js` will run in a JSDOM c
 
 By default Jest will not transform any `.marko` files within your `node_modules` folder. Marko recommends publishing the original source Marko files when publishing to npm. To get around this you can use the [`transformIgnorePatterns`](https://jestjs.io/docs/en/tutorial-react-native#transformignorepatterns-customization) option in Jest and whitelist any packages which contain Marko tags.
 
+The `@marko/jest` preset by will scan your `node_modules` and build the appropriate ignore pattern for you. If you are just using the `@marko/jest` transformer standalone then you will have to do this yourself, like so:
+
 **jest.config.js**
 
 ```javascript
 module.exports = {
-  browser: true,
-  preset: "@marko/jest",
-  transformIgnorePatterns: [
-    // `marko` is excluded automatically by the preset.
-    // Here we are also adding `@marko-tags` to allow using https://github.com/marko-js/tags
-    "node_modules/(?!(marko|@marko-tags)/)"
-  ]
+  ...,
+  transformIgnorePatterns: ["node_modules/(?!(marko|@marko-tags|another-package-with-marko-tags)/)"]
 };
 ```
 

jest-preset.js

@@ -1,4 +1,11 @@
+const fs = require("fs");
+const path = require("path");
 const { defaults } = require("jest-config");
+const escapeRegexp = require("escape-string-regexp");
+const { package, path: packagePath } = require("read-pkg-up").sync({
+  normalize: false
+});
+const nodeModulesPath = path.join(packagePath, "../node_modules");
 
 module.exports = {
   // uses a webpack style resolver, the default one has many issues.
@@ -7,8 +14,22 @@ module.exports = {
   moduleFileExtensions: defaults.moduleFileExtensions.concat("marko"),
   // preprocesses Marko files.
   transform: {
-    "\\.marko$": require.resolve(".")
+    "\\.marko$": require.resolve("."),
+    "\\.[tj]s$": "babel-jest"
   },
-  // transforms top level `.marko` files in the Marko package.
-  transformIgnorePatterns: ["node_modules/(?!(marko)/)"]
+  // Jest ignores node_module transforms by default.
+  // Here we whitelist all node_modules that contain a `marko.json`.
+  // Only checks for node_modules listed in package.json, same as Marko taglib scanning.
+  transformIgnorePatterns: [
+    `node_modules/(?!(${Object.keys(package.dependencies || {})
+      .concat(Object.keys(package.devDependencies || {}))
+      .concat(Object.keys(package.peerDependencies || {}))
+      .filter((name, i, all) => all.indexOf(name) === i)
+      .filter(name =>
+        fs.existsSync(path.join(nodeModulesPath, name, "marko.json"))
+      )
+      .map(escapeRegexp)
+      .concat("marko")
+      .join("|")})/)`
+  ]
 };