Bug 1670183 - Combine testHas and testGet methods for FOG C++ and JS r=janerik

Differential Revision: https://phabricator.services.mozilla.com/D97032

toolkit/components/glean/bindings/private/Counter.cpp

@@ -23,16 +23,15 @@ GleanCounter::Add(uint32_t amount, JSContext* cx) {
 }
 
 NS_IMETHODIMP
-GleanCounter::TestHasValue(const nsACString& aStorageName, JSContext* cx,
-                           bool* result) {
-  *result = this->mCounter.TestHasValue(PromiseFlatCString(aStorageName).get());
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-GleanCounter::TestGetValue(const nsACString& aStorageName, JSContext* cx,
-                           int32_t* result) {
-  *result = this->mCounter.TestGetValue(PromiseFlatCString(aStorageName).get());
+GleanCounter::TestGetValue(const nsACString& aStorageName,
+                           JS::MutableHandleValue aResult) {
+  auto result =
+      this->mCounter.TestGetValue(PromiseFlatCString(aStorageName).get());
+  if (result.isNothing()) {
+    aResult.set(JS::UndefinedValue());
+  } else {
+    aResult.set(JS::Int32Value(result.value()));
+  }
   return NS_OK;
 }
 

toolkit/components/glean/bindings/private/Counter.h

@@ -30,24 +30,6 @@ class CounterMetric {
    */
   void Add(int32_t amount = 1) const { fog_counter_add(mId, amount); }
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  bool TestHasValue(const char* aStorageName) const {
-    return fog_counter_test_has_value(mId, aStorageName) != 0;
-  }
-
   /**
    * **Test-only API**
    *
@@ -60,10 +42,13 @@ class CounterMetric {
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or Nothing() if there is no value.
    */
-  int32_t TestGetValue(const char* aStorageName) const {
-    return fog_counter_test_get_value(mId, aStorageName);
+  Maybe<int32_t> TestGetValue(const char* aStorageName) const {
+    if (!fog_counter_test_has_value(mId, aStorageName)) {
+      return Nothing();
+    }
+    return Some(fog_counter_test_get_value(mId, aStorageName));
   }
 
  private:

toolkit/components/glean/bindings/private/Datetime.cpp

@@ -31,18 +31,16 @@ GleanDatetime::Set(PRTime value, uint8_t optional_argc) {
 }
 
 NS_IMETHODIMP
-GleanDatetime::TestHasValue(const nsACString& aStorageName, JSContext* cx,
-                            bool* result) {
-  *result =
-      this->mDatetime.TestHasValue(PromiseFlatCString(aStorageName).get());
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-GleanDatetime::TestGetValue(const nsACString& aStorageName, JSContext* cx,
-                            nsACString& result) {
-  result.Assign(
-      this->mDatetime.TestGetValue(PromiseFlatCString(aStorageName).get()));
+GleanDatetime::TestGetValue(const nsACString& aStorageName, JSContext* aCx,
+                            JS::MutableHandleValue aResult) {
+  auto result = mDatetime.TestGetValue(PromiseFlatCString(aStorageName).get());
+  if (result.isNothing()) {
+    aResult.set(JS::UndefinedValue());
+  } else {
+    const NS_ConvertUTF8toUTF16 str(result.value());
+    aResult.set(
+        JS::StringValue(JS_NewUCStringCopyN(aCx, str.Data(), str.Length())));
+  }
   return NS_OK;
 }
 

toolkit/components/glean/bindings/private/Datetime.h

@@ -44,26 +44,8 @@ class DatetimeMetric {
     int32_t offset =
         exploded.tm_params.tp_gmt_offset + exploded.tm_params.tp_dst_offset;
     fog_datetime_set(mId, exploded.tm_year, exploded.tm_month + 1,
-                    exploded.tm_mday, exploded.tm_hour, exploded.tm_min,
-                    exploded.tm_sec, exploded.tm_usec * 1000, offset);
-  }
-
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  bool TestHasValue(const char* aStorageName) const {
-    return fog_datetime_test_has_value(mId, aStorageName) != 0;
+                     exploded.tm_mday, exploded.tm_hour, exploded.tm_min,
+                     exploded.tm_sec, exploded.tm_usec * 1000, offset);
   }
 
   /**
@@ -78,12 +60,15 @@ class DatetimeMetric {
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or Nothing() if there is no value.
    */
-  nsCString TestGetValue(const char* aStorageName) const {
+  Maybe<nsCString> TestGetValue(const char* aStorageName) const {
+    if (!fog_datetime_test_has_value(mId, aStorageName)) {
+      return Nothing();
+    }
     nsCString ret;
     fog_datetime_test_get_value(mId, aStorageName, ret);
-    return ret;
+    return Some(ret);
   }
 
  private:

toolkit/components/glean/bindings/private/String.cpp

@@ -22,18 +22,18 @@ GleanString::Set(const nsACString& value, JSContext* cx) {
   return NS_OK;
 }
 
-NS_IMETHODIMP
-GleanString::TestHasValue(const nsACString& aStorageName, JSContext* cx,
-                          bool* result) {
-  *result = this->mString.TestHasValue(PromiseFlatCString(aStorageName).get());
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 GleanString::TestGetValue(const nsACString& aStorageName, JSContext* cx,
-                          nsACString& result) {
-  result.Assign(
-      this->mString.TestGetValue(PromiseFlatCString(aStorageName).get()));
+                          JS::MutableHandleValue aResult) {
+  auto result =
+      this->mString.TestGetValue(PromiseFlatCString(aStorageName).get());
+  if (result.isNothing()) {
+    aResult.set(JS::UndefinedValue());
+  } else {
+    const NS_ConvertUTF8toUTF16 str(result.value());
+    aResult.set(
+        JS::StringValue(JS_NewUCStringCopyN(cx, str.Data(), str.Length())));
+  }
   return NS_OK;
 }
 

toolkit/components/glean/bindings/private/String.h

@@ -35,24 +35,6 @@ class StringMetric {
    */
   void Set(const nsACString& value) const { fog_string_set(mId, value); }
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  bool TestHasValue(const char* aStorageName) const {
-    return fog_string_test_has_value(mId, aStorageName) != 0;
-  }
-
   /**
    * **Test-only API**
    *
@@ -65,12 +47,15 @@ class StringMetric {
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or Nothing() if there is no value.
    */
-  nsCString TestGetValue(const char* aStorageName) const {
+  Maybe<nsCString> TestGetValue(const char* aStorageName) const {
+    if (!fog_string_test_has_value(mId, aStorageName)) {
+      return Nothing();
+    }
     nsCString ret;
     fog_string_test_get_value(mId, aStorageName, ret);
-    return ret;
+    return Some(ret);
   }
 
  private:

toolkit/components/glean/bindings/private/Timespan.cpp

@@ -29,18 +29,15 @@ GleanTimespan::Stop(JSContext* cx) {
 }
 
 NS_IMETHODIMP
-GleanTimespan::TestHasValue(const nsACString& aStorageName, JSContext* cx,
-                            bool* result) {
-  *result =
-      this->mTimespan.TestHasValue(PromiseFlatCString(aStorageName).get());
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-GleanTimespan::TestGetValue(const nsACString& aStorageName, JSContext* cx,
-                            int64_t* result) {
-  *result =
+GleanTimespan::TestGetValue(const nsACString& aStorageName,
+                            JS::MutableHandleValue aResult) {
+  auto result =
       this->mTimespan.TestGetValue(PromiseFlatCString(aStorageName).get());
+  if (result.isNothing()) {
+    aResult.set(JS::UndefinedValue());
+  } else {
+    aResult.set(JS::DoubleValue(result.value()));
+  }
   return NS_OK;
 }
 

toolkit/components/glean/bindings/private/Timespan.h

@@ -43,24 +43,6 @@ class TimespanMetric {
    */
   void Stop() const { fog_timespan_stop(mId); }
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  bool TestHasValue(const char* aStorageName) const {
-    return fog_timespan_test_has_value(mId, aStorageName) != 0;
-  }
-
   /**
    * **Test-only API**
    *
@@ -73,10 +55,13 @@ class TimespanMetric {
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or Nothing() if there is no value.
    */
-  int64_t TestGetValue(const char* aStorageName) const {
-    return fog_timespan_test_get_value(mId, aStorageName);
+  Maybe<int64_t> TestGetValue(const char* aStorageName) const {
+    if (!fog_timespan_test_has_value(mId, aStorageName)) {
+      return Nothing();
+    }
+    return Some(fog_timespan_test_get_value(mId, aStorageName));
   }
 
  private:

toolkit/components/glean/bindings/private/Uuid.cpp

@@ -28,18 +28,18 @@ GleanUuid::GenerateAndSet(JSContext* cx) {
   return NS_OK;
 }
 
-NS_IMETHODIMP
-GleanUuid::TestHasValue(const nsACString& aStorageName, JSContext* cx,
-                        bool* result) {
-  *result = this->mUuid.TestHasValue(PromiseFlatCString(aStorageName).get());
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 GleanUuid::TestGetValue(const nsACString& aStorageName, JSContext* cx,
-                        nsACString& result) {
-  result.Assign(
-      this->mUuid.TestGetValue(PromiseFlatCString(aStorageName).get()));
+                        JS::MutableHandleValue aResult) {
+  auto result =
+      this->mUuid.TestGetValue(PromiseFlatCString(aStorageName).get());
+  if (result.isNothing()) {
+    aResult.set(JS::UndefinedValue());
+  } else {
+    const NS_ConvertUTF8toUTF16 str(result.value());
+    aResult.set(
+        JS::StringValue(JS_NewUCStringCopyN(cx, str.Data(), str.Length())));
+  }
   return NS_OK;
 }
 

toolkit/components/glean/bindings/private/Uuid.h

@@ -38,24 +38,6 @@ class UuidMetric {
    */
   void GenerateAndSet() const { fog_uuid_generate_and_set(mId); }
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  bool TestHasValue(const char* aStorageName) const {
-    return fog_uuid_test_has_value(mId, aStorageName) != 0;
-  }
-
   /**
    * **Test-only API**
    *
@@ -69,12 +51,15 @@ class UuidMetric {
    * Parent process only. Panics in child processes.
    * Panics if there is no value to get.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or Nothing() if there is no value.
    */
-  nsCString TestGetValue(const char* aStorageName) const {
+  Maybe<nsCString> TestGetValue(const char* aStorageName) const {
+    if (!fog_uuid_test_has_value(mId, aStorageName)) {
+      return Nothing();
+    }
     nsCString ret;
     fog_uuid_test_get_value(mId, aStorageName, ret);
-    return ret;
+    return Some(ret);
   }
 
  private:

toolkit/components/glean/docs/new_metric_types.md

@@ -89,6 +89,9 @@ Each metric type has six pieces you'll need to cover:
    [`bindings/private/`](https://hg.mozilla.org/mozilla-central/file/tip/toolkit/components/glean/bindings/private/).
    Its methods should be named the same as the ones in the Rust API,
    transformed to `CamelCase`. They should all be public.
+   Multiplex the FFI's `test_have` and `test_get` functions into a single
+   `TestGetValue` function that returns a
+   `mozilla::Maybe` wrapping the C++ type that best fits the metric type.
 3. **IDL** - Duplicate the public API (including its docs) to
    [`xpcom/nsIGleanMetrics.idl`](https://hg.mozilla.org/mozilla-central/file/tip/toolkit/components/glean/xpcom/nsIGleanMetrics.idl)
    with the name `nsIGleanX` (e.g. `nsIGleanCounter`).
@@ -98,6 +101,7 @@ Each metric type has six pieces you'll need to cover:
    [GUID](https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Generating_GUIDs)
    because this is XPCOM,
    but you'll only need the canonical form since we're only exposing to JS.
+   The `testGetValue` method will return a `jsval`.
 4. **JS Impl** - Add an `nsIGleanX`-deriving, `XMetric`-owning type called `GleanX`
    (e.g. `GleanCounter`) in the same header and `.cpp` as `XMetric` in
    [`bindings/private/`](https://hg.mozilla.org/mozilla-central/file/tip/toolkit/components/glean/bindings/private/).
@@ -109,7 +113,9 @@ Each metric type has six pieces you'll need to cover:
    `CamelCase` and need macros like `NS_IMETHODIMP`.
    Delegate operations to the owned `XMetric`, returning `NS_OK`
    no matter what in non-test methods.
-   (Test-only methods can return `NS_ERROR` codes on failures).
+   Test-only methods can return `NS_ERROR` codes on failures,
+   but mostly return `NS_OK` and use `undefined` in the
+   `JS::MutableHandleValue` result to signal no value.
 5. **Tests** - Two languages means two test suites.
    Add a never-expiring test-only metric of your type to
    [`test_metrics.yaml`](https://hg.mozilla.org/mozilla-central/file/tip/toolkit/components/glean/test_metrics.yaml).

toolkit/components/glean/gtest/TestFog.cpp

@@ -56,8 +56,9 @@ TEST(FOG, TestCppCounterWorks)
 {
   mozilla::glean::test_only::bad_code.Add(42);
 
-  ASSERT_TRUE(mozilla::glean::test_only::bad_code.TestHasValue("test-ping"));
-  ASSERT_EQ(42, mozilla::glean::test_only::bad_code.TestGetValue("test-ping"));
+  ASSERT_EQ(
+      42,
+      mozilla::glean::test_only::bad_code.TestGetValue("test-ping").value());
 }
 
 TEST(FOG, TestCppStringWorks)
@@ -65,11 +66,10 @@ TEST(FOG, TestCppStringWorks)
   auto kValue = "cheez!"_ns;
   mozilla::glean::test_only::cheesy_string.Set(kValue);
 
-  ASSERT_TRUE(
-      mozilla::glean::test_only::cheesy_string.TestHasValue("test-ping"));
-  ASSERT_STREQ(
-      kValue.get(),
-      mozilla::glean::test_only::cheesy_string.TestGetValue("test-ping").get());
+  ASSERT_STREQ(kValue.get(), mozilla::glean::test_only::cheesy_string
+                                 .TestGetValue("test-ping")
+                                 .value()
+                                 .get());
 }
 
 TEST(FOG, TestCppTimespanWorks)
@@ -79,34 +79,29 @@ TEST(FOG, TestCppTimespanWorks)
   mozilla::glean::test_only::can_we_time_it.Stop();
 
   ASSERT_TRUE(
-      mozilla::glean::test_only::can_we_time_it.TestHasValue("test-ping"));
-  ASSERT_TRUE(
-      mozilla::glean::test_only::can_we_time_it.TestGetValue("test-ping") > 0);
+      mozilla::glean::test_only::can_we_time_it.TestGetValue("test-ping")
+          .value() > 0);
 }
 
 TEST(FOG, TestCppUuidWorks)
 {
   nsCString kTestUuid("decafdec-afde-cafd-ecaf-decafdecafde");
   test_only::what_id_it.Set(kTestUuid);
-  ASSERT_TRUE(test_only::what_id_it.TestHasValue("test-ping"));
   ASSERT_STREQ(kTestUuid.get(),
-               test_only::what_id_it.TestGetValue("test-ping").get());
+               test_only::what_id_it.TestGetValue("test-ping").value().get());
 
   test_only::what_id_it.GenerateAndSet();
   // Since we generate v4 UUIDs, and the first character of the third group
   // isn't 4, this won't ever collide with kTestUuid.
   ASSERT_STRNE(kTestUuid.get(),
-               test_only::what_id_it.TestGetValue("test-ping").get());
+               test_only::what_id_it.TestGetValue("test-ping").value().get());
 }
 
 TEST(FOG, TestCppDatetimeWorks)
 {
   PRExplodedTime date = {0, 35, 10, 12, 6, 10, 2020, 0, 0, {5 * 60 * 60, 0}};
-  mozilla::glean::test_only::what_a_date.Set(&date);
-  ASSERT_TRUE(mozilla::glean::test_only::what_a_date.TestHasValue("test-ping"));
+  test_only::what_a_date.Set(&date);
 
-  nsCString received;
-  received.Assign(
-      mozilla::glean::test_only::what_a_date.TestGetValue("test-ping"));
-  ASSERT_STREQ(received.get(), "2020-11-06T12:10:35+05:00");
+  auto received = test_only::what_a_date.TestGetValue("test-ping");
+  ASSERT_STREQ(received.value().get(), "2020-11-06T12:10:35+05:00");
 }

toolkit/components/glean/xpcom/nsIGleanMetrics.idl

@@ -16,23 +16,6 @@ interface nsIGleanDatetime : nsISupports
   [optional_argc]
   void set([optional] in PRTime value);
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  [implicit_jscontext]
-  bool testHasValue(in ACString aStorageName);
-
   /**
    * **Test-only API**
    *
@@ -45,10 +28,10 @@ interface nsIGleanDatetime : nsISupports
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or undefined if there is no value.
    */
   [implicit_jscontext]
-  ACString testGetValue(in ACString aStorageName);
+  jsval testGetValue(in ACString aStorageName);
 };
 
 [scriptable, uuid(05b89d2a-d57c-11ea-82da-3f63399a6f5a)]
@@ -62,23 +45,6 @@ interface nsIGleanCounter : nsISupports
   [implicit_jscontext]
   void add(in uint32_t amount);
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  [implicit_jscontext]
-  bool testHasValue(in ACString aStorageName);
-
   /**
    * **Test-only API**
    *
@@ -91,10 +57,9 @@ interface nsIGleanCounter : nsISupports
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or undefined if there is no value.
    */
-  [implicit_jscontext]
-  long testGetValue(in ACString aStorageName);
+  jsval testGetValue(in ACString aStorageName);
 };
 
 [scriptable, uuid(d84a3555-46f1-48c1-9122-e8e88b069d2b)]
@@ -108,23 +73,6 @@ interface nsIGleanString : nsISupports
   [implicit_jscontext]
   void set(in ACString value);
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  [implicit_jscontext]
-  bool testHasValue(in ACString aStorageName);
-
   /**
    * **Test-only API**
    *
@@ -137,10 +85,10 @@ interface nsIGleanString : nsISupports
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or undefined if there is no value.
    */
   [implicit_jscontext]
-  ACString testGetValue(in ACString aStorageName);
+  jsval testGetValue(in ACString aStorageName);
 };
 
 [scriptable, uuid(2586530c-030f-11eb-93cb-cbf30d25225a)]
@@ -167,23 +115,6 @@ interface nsIGleanTimespan : nsISupports
   [implicit_jscontext]
   void stop();
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  [implicit_jscontext]
-  bool testHasValue(in ACString aStorageName);
-
   /**
    * **Test-only API**
    *
@@ -196,10 +127,9 @@ interface nsIGleanTimespan : nsISupports
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or undefined if there is no value.
    */
-  [implicit_jscontext]
-  long long testGetValue(in ACString aStorageName);
+  jsval testGetValue(in ACString aStorageName);
 };
 
 [scriptable, uuid(395700e7-06f6-46be-adcc-ea58977fda6d)]
@@ -219,23 +149,6 @@ interface nsIGleanUuid : nsISupports
   [implicit_jscontext]
   void generateAndSet();
 
-  /**
-   * **Test-only API**
-   *
-   * Tests whether a value is stored for the metric.
-   *
-   * This function will attempt to await the last parent-process task (if any)
-   * writing to the the metric's storage engine before returning a value.
-   * This function will not wait for data from child processes.
-   *
-   * Parent process only. Panics in child processes.
-   *
-   * @param aStorageName the name of the ping to retrieve the metric for.
-   * @return true if metric value exists, otherwise false
-   */
-  [implicit_jscontext]
-  bool testHasValue(in ACString aStorageName);
-
   /**
    * **Test-only API**
    *
@@ -248,8 +161,8 @@ interface nsIGleanUuid : nsISupports
    * This doesn't clear the stored value.
    * Parent process only. Panics in child processes.
    *
-   * @return value of the stored metric.
+   * @return value of the stored metric, or undefined if there is no value.
    */
   [implicit_jscontext]
-  ACString testGetValue(in ACString aStorageName);
+  jsval testGetValue(in ACString aStorageName);
 };

toolkit/components/glean/xpcshell/test_Glean.js

@@ -28,7 +28,6 @@ add_task(function test_setup() {
 
 add_task(function test_fog_counter_works() {
   Glean.test_only.bad_code.add(31);
-  Assert.ok(Glean.test_only.bad_code.testHasValue("test-ping"));
   Assert.equal(31, Glean.test_only.bad_code.testGetValue("test-ping"));
 });
 
@@ -36,7 +35,6 @@ add_task(async function test_fog_string_works() {
   const value = "a cheesy string!";
   Glean.test_only.cheesy_string.set(value);
 
-  Assert.ok(Glean.test_only.cheesy_string.testHasValue("test-ping"));
   Assert.equal(value, Glean.test_only.cheesy_string.testGetValue("test-ping"));
 });
 
@@ -47,14 +45,12 @@ add_task(async function test_fog_timespan_works() {
   await sleep(10);
   Glean.test_only.can_we_time_it.stop();
 
-  Assert.ok(Glean.test_only.can_we_time_it.testHasValue("test-ping"));
   Assert.ok(Glean.test_only.can_we_time_it.testGetValue("test-ping") > 0);
 });
 
 add_task(async function test_fog_uuid_works() {
   const kTestUuid = "decafdec-afde-cafd-ecaf-decafdecafde";
   Glean.test_only.what_id_it.set(kTestUuid);
-  Assert.ok(Glean.test_only.what_id_it.testHasValue("test-ping"));
   Assert.equal(kTestUuid, Glean.test_only.what_id_it.testGetValue("test-ping"));
 
   Glean.test_only.what_id_it.generateAndSet();
@@ -70,7 +66,6 @@ add_task(function test_fog_datetime_works() {
   const value = new Date("2020-06-11T12:00:00");
 
   Glean.test_only.what_a_date.set(value.getTime() * 1000);
-  Assert.ok(Glean.test_only.what_a_date.testHasValue("test-ping"));
 
   const received = Glean.test_only.what_a_date.testGetValue("test-ping");
   Assert.ok(received.startsWith("2020-06-11T12:00:00"));