Backport minNodeVersion test option from babel#5765 for 6.x

CONTRIBUTING.md

@@ -195,6 +195,15 @@ If you need to check for an error that is thrown you can add to the `options.jso
 }
 ```
 
+If the test requires a minimum Node version, you can add `minNodeVersion` (must be in semver format).
+
+```js
+// options.json example
+{
+  "minNodeVersion": "5.0.0"
+}
+```
+
 #### Bootstrapping expected output
 
 For both `babel-plugin-x` and `babylon`, you can easily generate an `expected.js`/`expected.json` automatically by just providing `actual.js` and running the tests as you usually would.

packages/babel-helper-fixtures/package.json

@@ -9,6 +9,7 @@
   "dependencies": {
     "babel-runtime": "^6.26.0",
     "lodash": "^4.17.4",
-    "try-resolve": "^1.0.1"
+    "try-resolve": "^1.0.1",
+    "semver": "^5.3.0"
   }
 }

packages/babel-helper-fixtures/src/index.js

@@ -3,9 +3,12 @@ import trimEnd from "lodash/trimEnd";
 import resolve from "try-resolve";
 import clone from "lodash/clone";
 import merge from "lodash/merge";
+import semver from "semver";
 import path from "path";
 import fs from "fs";
 
+const nodeVersion = semver.clean(process.version.slice(1));
+
 function humanize(val, noext) {
   if (noext) val = path.basename(val, path.extname(val));
   return val.replace(/-/g, " ");
@@ -125,6 +128,22 @@ export default function get(entryLoc): Array<Suite> {
         }
       };
 
+      // If there's node requirement, check it before pushing task
+      if (taskOpts.minNodeVersion) {
+        const minimumVersion = semver.clean(taskOpts.minNodeVersion);
+
+        if (minimumVersion == null) {
+          throw new Error(`'minNodeVersion' has invalid semver format: ${taskOpts.minNodeVersion}`);
+        }
+
+        if (semver.lt(nodeVersion, minimumVersion)) {
+          return;
+        }
+
+        // Delete to avoid option validation error
+        delete taskOpts.minNodeVersion;
+      }
+
       // traceur checks
 
       if (test.exec.code.indexOf("// Async.") >= 0) {