Add tests for TaskbarUnitTestRule.

Test: TaskbarUnitTestRuleTest
Bug: 230027385
Flag: TEST_ONLY
Change-Id: I1c17b7f04920676cdfbe481b9435ff5d842181d1
diff --git a/quickstep/tests/multivalentTests/src/com/android/launcher3/taskbar/rules/TaskbarUnitTestRuleTest.kt b/quickstep/tests/multivalentTests/src/com/android/launcher3/taskbar/rules/TaskbarUnitTestRuleTest.kt
new file mode 100644
index 0000000..ef8c548
--- /dev/null
+++ b/quickstep/tests/multivalentTests/src/com/android/launcher3/taskbar/rules/TaskbarUnitTestRuleTest.kt
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2024 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.launcher3.taskbar.rules
+
+import androidx.test.platform.app.InstrumentationRegistry.getInstrumentation
+import com.android.launcher3.taskbar.TaskbarActivityContext
+import com.android.launcher3.taskbar.TaskbarKeyguardController
+import com.android.launcher3.taskbar.TaskbarManager
+import com.android.launcher3.taskbar.TaskbarStashController
+import com.android.launcher3.taskbar.rules.TaskbarUnitTestRule.InjectController
+import com.android.launcher3.util.LauncherMultivalentJUnit
+import com.android.launcher3.util.LauncherMultivalentJUnit.EmulatedDevices
+import com.android.launcher3.util.MainThreadInitializedObject.SandboxContext
+import com.google.common.truth.Truth.assertThat
+import org.junit.Assert.assertThrows
+import org.junit.Test
+import org.junit.runner.Description
+import org.junit.runner.RunWith
+import org.junit.runners.model.Statement
+
+@RunWith(LauncherMultivalentJUnit::class)
+@EmulatedDevices(["pixelFoldable2023"])
+class TaskbarUnitTestRuleTest {
+
+    private val context = SandboxContext(getInstrumentation().targetContext)
+
+    @Test
+    fun testSetup_taskbarInitialized() {
+        onSetup { assertThat(activityContext).isInstanceOf(TaskbarActivityContext::class.java) }
+    }
+
+    @Test
+    fun testRecreateTaskbar_activityContextChanged() {
+        onSetup {
+            val context1 = activityContext
+            recreateTaskbar()
+            val context2 = activityContext
+            assertThat(context1).isNotSameInstanceAs(context2)
+        }
+    }
+
+    @Test
+    fun testTeardown_taskbarDestroyed() {
+        val testRule = TaskbarUnitTestRule(this, context)
+        testRule.apply(EMPTY_STATEMENT, DESCRIPTION).evaluate()
+        assertThrows(RuntimeException::class.java) { testRule.activityContext }
+    }
+
+    @Test
+    fun testInjectController_validControllerType_isInjected() {
+        val testClass =
+            object {
+                @InjectController lateinit var controller: TaskbarStashController
+                val isInjected: Boolean
+                    get() = ::controller.isInitialized
+            }
+
+        TaskbarUnitTestRule(testClass, context).apply(EMPTY_STATEMENT, DESCRIPTION).evaluate()
+
+        onSetup(TaskbarUnitTestRule(testClass, context)) {
+            assertThat(testClass.isInjected).isTrue()
+        }
+    }
+
+    @Test
+    fun testInjectController_multipleControllers_areInjected() {
+        val testClass =
+            object {
+                @InjectController lateinit var controller1: TaskbarStashController
+                @InjectController lateinit var controller2: TaskbarKeyguardController
+                val areInjected: Boolean
+                    get() = ::controller1.isInitialized && ::controller2.isInitialized
+            }
+
+        onSetup(TaskbarUnitTestRule(testClass, context)) {
+            assertThat(testClass.areInjected).isTrue()
+        }
+    }
+
+    @Test
+    fun testInjectController_invalidControllerType_exceptionThrown() {
+        val testClass =
+            object {
+                @InjectController lateinit var manager: TaskbarManager // Not a controller.
+            }
+
+        // We cannot use #assertThrows because we also catch an assumption violated exception when
+        // running #evaluate on devices that do not support Taskbar.
+        val result =
+            try {
+                TaskbarUnitTestRule(testClass, context)
+                    .apply(EMPTY_STATEMENT, DESCRIPTION)
+                    .evaluate()
+            } catch (e: NoSuchElementException) {
+                e
+            }
+        assertThat(result).isInstanceOf(NoSuchElementException::class.java)
+    }
+
+    @Test
+    fun testInjectController_recreateTaskbar_controllerChanged() {
+        val testClass =
+            object {
+                @InjectController lateinit var controller: TaskbarStashController
+            }
+
+        onSetup(TaskbarUnitTestRule(testClass, context)) {
+            val controller1 = testClass.controller
+            recreateTaskbar()
+            val controller2 = testClass.controller
+            assertThat(controller1).isNotSameInstanceAs(controller2)
+        }
+    }
+
+    /** Executes [runTest] after the [testRule] setup phase completes. */
+    private fun onSetup(
+        testRule: TaskbarUnitTestRule = TaskbarUnitTestRule(this, context),
+        runTest: TaskbarUnitTestRule.() -> Unit,
+    ) {
+        testRule
+            .apply(
+                object : Statement() {
+                    override fun evaluate() = runTest(testRule)
+                },
+                DESCRIPTION,
+            )
+            .evaluate()
+    }
+
+    private companion object {
+        private val EMPTY_STATEMENT =
+            object : Statement() {
+                override fun evaluate() = Unit
+            }
+        private val DESCRIPTION =
+            Description.createSuiteDescription(TaskbarUnitTestRuleTest::class.java)
+    }
+}