Add RefactorFlagUtils and an example usage

Fixes: 303809202
Test: atest SystemUITests
Change-Id: Id2a5e113d76032496a654f3e9c2dee5c0a7e3a21

packages/SystemUI/src/com/android/systemui/flags/RefactorFlag.kt

@@ -16,7 +16,6 @@
 
 package com.android.systemui.flags
 
-import android.util.Log
 import com.android.systemui.Dependency
 
 /**
@@ -65,8 +64,7 @@ private constructor(
      * }
      * ````
      */
-    fun assertInLegacyMode() =
-        check(!isEnabled) { "Legacy code path not supported when $flagName is enabled." }
+    fun assertInLegacyMode() = RefactorFlagUtils.assertInLegacyMode(isEnabled, flagName)
 
     /**
      * Called to ensure code is only run when the flag is enabled. This protects users from the
@@ -81,13 +79,8 @@ private constructor(
      * }
      * ```
      */
-    fun isUnexpectedlyInLegacyMode(): Boolean {
-        if (!isEnabled) {
-            val message = "New code path expects $flagName to be enabled."
-            Log.wtf(TAG, message, Exception(message))
-        }
-        return !isEnabled
-    }
+    fun isUnexpectedlyInLegacyMode(): Boolean =
+        RefactorFlagUtils.isUnexpectedlyInLegacyMode(isEnabled, flagName)
 
     companion object {
         private const val TAG = "RefactorFlag"

packages/SystemUI/src/com/android/systemui/flags/RefactorFlagUtils.kt

+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.flags
+
+import android.util.Log
+
+/**
+ * Utilities for writing your own objects to uphold refactor flag conventions.
+ *
+ * Example usage:
+ * ```
+ * object SomeRefactor {
+ *     const val FLAG_NAME = Flags.SOME_REFACTOR
+ *     @JvmStatic inline val isEnabled get() = Flags.someRefactor()
+ *     @JvmStatic inline fun isUnexpectedlyInLegacyMode() =
+ *         RefactorFlagUtils.isUnexpectedlyInLegacyMode(isEnabled, FLAG_NAME)
+ *     @JvmStatic inline fun assertInLegacyMode() =
+ *         RefactorFlagUtils.assertInLegacyMode(isEnabled, FLAG_NAME)
+ * }
+ * ```
+ */
+@Suppress("NOTHING_TO_INLINE")
+object RefactorFlagUtils {
+    /**
+     * Called to ensure code is only run when the flag is enabled. This protects users from the
+     * unintended behaviors caused by accidentally running new logic, while also crashing on an eng
+     * build to ensure that the refactor author catches issues in testing.
+     *
+     * Example usage:
+     * ```
+     * public void setNewController(SomeController someController) {
+     *     if (SomeRefactor.isUnexpectedlyInLegacyMode()) return;
+     *     mSomeController = someController;
+     * }
+     * ```
+     */
+    inline fun isUnexpectedlyInLegacyMode(isEnabled: Boolean, flagName: Any): Boolean {
+        val inLegacyMode = !isEnabled
+        if (inLegacyMode) {
+            val message = "New code path expects $flagName to be enabled."
+            Log.wtf("RefactorFlag", message, IllegalStateException(message))
+        }
+        return inLegacyMode
+    }
+
+    /**
+     * Called to ensure code is only run when the flag is disabled. This will throw an exception if
+     * the flag is enabled to ensure that the refactor author catches issues in testing.
+     *
+     * Example usage:
+     * ```
+     * public void setSomeLegacyController(SomeController someController) {
+     *     SomeRefactor.assertInLegacyMode();
+     *     mSomeController = someController;
+     * }
+     * ````
+     */
+    inline fun assertInLegacyMode(isEnabled: Boolean, flagName: Any) =
+        check(!isEnabled) { "Legacy code path not supported when $flagName is enabled." }
+}

packages/SystemUI/src/com/android/systemui/statusbar/notification/footer/shared/FooterViewRefactor.kt

+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.statusbar.notification.footer.shared
+
+import com.android.systemui.Flags
+import com.android.systemui.flags.RefactorFlagUtils
+
+/** Helper for reading or using the FooterView refactor flag state. */
+@Suppress("NOTHING_TO_INLINE")
+object FooterViewRefactor {
+    const val FLAG_NAME = Flags.FLAG_NOTIFICATIONS_FOOTER_VIEW_REFACTOR
+
+    /** Is the refactor enabled */
+    @JvmStatic
+    inline val isEnabled
+        get() = Flags.notificationsFooterViewRefactor()
+
+    /**
+     * Called to ensure code is only run when the flag is enabled. This protects users from the
+     * unintended behaviors caused by accidentally running new logic, while also crashing on an eng
+     * build to ensure that the refactor author catches issues in testing.
+     */
+    @JvmStatic
+    inline fun isUnexpectedlyInLegacyMode() =
+        RefactorFlagUtils.isUnexpectedlyInLegacyMode(isEnabled, FLAG_NAME)
+
+    /**
+     * Called to ensure code is only run when the flag is disabled. This will throw an exception if
+     * the flag is enabled to ensure that the refactor author catches issues in testing.
+     */
+    @JvmStatic
+    inline fun assertInLegacyMode() = RefactorFlagUtils.assertInLegacyMode(isEnabled, FLAG_NAME)
+}