Add isInDebug variable to simulate debug/release configs for tests (#2566)

* `isInDebug` as `ThreadLocal<Boolean>`

* Use a simple var for `isInDebug` and add a helper method to test release mode, when running the debug test.

* Add some more docs

---------

Co-authored-by: Benoit Marty <benoit@matrix.org>

tests/testutils/build.gradle.kts

@@ -30,6 +30,7 @@ dependencies {
     implementation(libs.test.junit)
     implementation(libs.test.truth)
     implementation(libs.coroutines.test)
+    implementation(projects.libraries.androidutils)
     implementation(projects.libraries.architecture)
     implementation(projects.libraries.core)
     implementation(projects.libraries.uiStrings)

tests/testutils/src/main/kotlin/io/element/android/tests/testutils/AssertThrowInDebug.kt

@@ -16,13 +16,14 @@
 
 package io.element.android.tests.testutils
 
+import io.element.android.libraries.androidutils.metadata.isInDebug
 import org.junit.Assert.assertThrows
 
 /**
  * Assert that the lambda throws only on debug mode.
  */
 fun assertThrowsInDebug(lambda: () -> Any?) {
-    if (BuildConfig.DEBUG) {
+    if (isInDebug) {
         assertThrows(IllegalStateException::class.java) {
             lambda()
         }

tests/testutils/src/main/kotlin/io/element/android/tests/testutils/IsInDebug.kt

@@ -1,22 +0,0 @@
-/*
- * Copyright (c) 2023 New Vector Ltd
- *
- * 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 io.element.android.tests.testutils
-
-/**
- * Returns true if the app is in debug mode.
- */
-fun isInDebug() = BuildConfig.DEBUG