1 files changed, 141 insertions, 0 deletions
diff --git a/toolkit/components/featuregates/test/unit/test_FeatureGateImplementation.js b/toolkit/components/featuregates/test/unit/test_FeatureGateImplementation.js
new file mode 100644
index 0000000000..ac844b4880
--- /dev/null
+++ b/toolkit/components/featuregates/test/unit/test_FeatureGateImplementation.js
@@ -0,0 +1,141 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { FeatureGateImplementation } = ChromeUtils.importESModule(
+  "resource://featuregates/FeatureGateImplementation.sys.mjs"
+);
+
+const kDefinitionDefaults = {
+  id: "test-feature",
+  title: "Test Feature",
+  description: "A feature for testing",
+  restartRequired: false,
+  type: "boolean",
+  preference: "test.feature",
+  defaultValue: false,
+  isPublic: false,
+};
+
+function definitionFactory(override = {}) {
+  return Object.assign({}, kDefinitionDefaults, override);
+}
+
+// getValue should work
+add_task(async function testGetValue() {
+  const preference = "test.pref";
+  equal(
+    Services.prefs.getPrefType(preference),
+    Services.prefs.PREF_INVALID,
+    "Before creating the feature gate, the preference should not exist"
+  );
+  const feature = new FeatureGateImplementation(
+    definitionFactory({ preference, defaultValue: false })
+  );
+  equal(
+    Services.prefs.getPrefType(preference),
+    Services.prefs.PREF_INVALID,
+    "Instantiating a feature gate should not set its default value"
+  );
+  equal(
+    await feature.getValue(),
+    false,
+    "getValue() should return the feature gate's default"
+  );
+
+  Services.prefs.setBoolPref(preference, true);
+  equal(
+    await feature.getValue(),
+    true,
+    "getValue() should return the new value"
+  );
+
+  Services.prefs.setBoolPref(preference, false);
+  equal(
+    await feature.getValue(),
+    false,
+    "getValue() should return the third value"
+  );
+
+  // cleanup
+  Services.prefs.getDefaultBranch("").deleteBranch(preference);
+});
+
+// event observers should work
+add_task(async function testGetValue() {
+  const preference = "test.pref";
+  const feature = new FeatureGateImplementation(
+    definitionFactory({ preference, defaultValue: false })
+  );
+  const observer = {
+    onChange: sinon.stub(),
+    onEnable: sinon.stub(),
+    onDisable: sinon.stub(),
+  };
+
+  let rv = await feature.addObserver(observer);
+  equal(rv, false, "addObserver returns the current value");
+
+  Assert.deepEqual(observer.onChange.args, [], "onChange should not be called");
+  Assert.deepEqual(observer.onEnable.args, [], "onEnable should not be called");
+  Assert.deepEqual(
+    observer.onDisable.args,
+    [],
+    "onDisable should not be called"
+  );
+
+  Services.prefs.setBoolPref(preference, true);
+  await Promise.resolve(); // Allow events to be called async
+  Assert.deepEqual(
+    observer.onChange.args,
+    [[true]],
+    "onChange should be called with the new value"
+  );
+  Assert.deepEqual(observer.onEnable.args, [[]], "onEnable should be called");
+  Assert.deepEqual(
+    observer.onDisable.args,
+    [],
+    "onDisable should not be called"
+  );
+
+  Services.prefs.setBoolPref(preference, false);
+  await Promise.resolve(); // Allow events to be called async
+  Assert.deepEqual(
+    observer.onChange.args,
+    [[true], [false]],
+    "onChange should be called again with the new value"
+  );
+  Assert.deepEqual(
+    observer.onEnable.args,
+    [[]],
+    "onEnable should not be called a second time"
+  );
+  Assert.deepEqual(
+    observer.onDisable.args,
+    [[]],
+    "onDisable should be called for the first time"
+  );
+
+  Services.prefs.setBoolPref(preference, false);
+  await Promise.resolve(); // Allow events to be called async
+  Assert.deepEqual(
+    observer.onChange.args,
+    [[true], [false]],
+    "onChange should not be called if the value did not change"
+  );
+  Assert.deepEqual(
+    observer.onEnable.args,
+    [[]],
+    "onEnable should not be called again if the value did not change"
+  );
+  Assert.deepEqual(
+    observer.onDisable.args,
+    [[]],
+    "onDisable should not be called if the value did not change"
+  );
+
+  // cleanup
+  feature.removeAllObservers();
+  Services.prefs.getDefaultBranch("").deleteBranch(preference);
+});