1 files changed, 83 insertions, 0 deletions
diff --git a/testing/web-platform/tests/common/subset-tests-by-key.js b/testing/web-platform/tests/common/subset-tests-by-key.js
new file mode 100644
index 0000000000..483017a644
--- /dev/null
+++ b/testing/web-platform/tests/common/subset-tests-by-key.js
@@ -0,0 +1,83 @@
+(function() {
+  var subTestKeyPattern = null;
+  var match;
+  var collectKeys = false;
+  var collectCounts = false;
+  var keys = {};
+  var exclude = false;
+  if (location.search) {
+    match = /(?:^\?|&)(include|exclude)=([^&]+)?/.exec(location.search);
+    if (match) {
+      subTestKeyPattern = new RegExp(`^${match[2]}$`);
+      if (match[1] === 'exclude') {
+        exclude = true;
+      }
+    }
+    // Below is utility code to generate <meta> for copy/paste into tests.
+    // Sample usage:
+    // test.html?get-keys
+    match = /(?:^\?|&)get-keys(&get-counts)?(?:&|$)/.exec(location.search);
+    if (match) {
+      collectKeys = true;
+      if (match[1]) {
+        collectCounts = true;
+      }
+      add_completion_callback(() => {
+        var metas = [];
+        var template = '<meta name="variant" content="?include=%s">';
+        if (collectCounts) {
+          template += ' <!--%s-->';
+        }
+        for (var key in keys) {
+          var meta = template.replace("%s", key);
+          if (collectCounts) {
+            meta = meta.replace("%s", keys[key]);
+          }
+          metas.push(meta);
+        }
+        var pre = document.createElement('pre');
+        pre.textContent = metas.join('\n') + '\n';
+        document.body.insertBefore(pre, document.body.firstChild);
+        document.getSelection().selectAllChildren(pre);
+      });
+    }
+  }
+  /**
+   * Check if `key` is in the subset specified in the URL.
+   * @param {string} key
+   * @returns {boolean}
+   */
+  function shouldRunSubTest(key) {
+    if (key && subTestKeyPattern) {
+      var found = subTestKeyPattern.test(key);
+      if (exclude) {
+        return !found;
+      }
+      return found;
+    }
+    return true;
+  }
+  /**
+   * Only test a subset of tests with `?include=Foo` or `?exclude=Foo` in the URL.
+   * Can be used together with `<meta name="variant" content="...">`
+   * Sample usage:
+   * for (const test of tests) {
+   *   subsetTestByKey("Foo", async_test, test.fn, test.name);
+   * }
+   */
+   function subsetTestByKey(key, testFunc, ...args) {
+    if (collectKeys) {
+      if (collectCounts && key in keys) {
+        keys[key]++;
+      } else {
+        keys[key] = 1;
+      }
+    }
+    if (shouldRunSubTest(key)) {
+      return testFunc(...args);
+    }
+    return null;
+  }
+  self.shouldRunSubTest = shouldRunSubTest;
+  self.subsetTestByKey = subsetTestByKey;
+})();