Fix flaky tests due to shared system property

The system property is shared within JVM, change system property in a test case might break test cases in another test class. To address the issue, introduce SystemProperty helper class to back up and restore the system properties in tests. Bug: 373177618 Flag: EXEMPT Test only Test: atest SettingsRoboTests Change-Id: I15539ce5ac425f35571d796baa25f259df1b601f
2024-10-15 16:43:05 +08:00
parent 8d30101228
commit 3ab6b197a9
4 changed files with 86 additions and 10 deletions
--- a/tests/robotests/testutils/com/android/settings/testutils/SystemProperty.kt
+++ b/tests/robotests/testutils/com/android/settings/testutils/SystemProperty.kt
@@ -0,0 +1,64 @@
+/*
+ * 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.settings.testutils
+
+/**
+ * Helper class to override system properties.
+ *
+ * [System.setProperty] changes the static state in the JVM, which is shared by all tests. Hence,
+ * there is chance that test cases are dependent/interfered due to system property unexpectedly.
+ * This helper class backs up the old properties when invoking [override] and restore the old
+ * properties in [close] to avoid flaky testing.
+ */
+class SystemProperty(overrides: Map<String, String?> = mapOf()) : AutoCloseable {
+    private val oldProperties = mutableMapOf<String, String?>()
+
+    constructor(key: String, value: String?) : this(mapOf(key to value))
+
+    init {
+        override(overrides)
+    }
+
+    fun override(key: String, value: String?) = override(mapOf(key to value))
+
+    fun override(overrides: Map<String, String?>) {
+        // back up system properties for the overrides
+        for (key in overrides.keys) {
+            // only back up the oldest property
+            if (!oldProperties.containsKey(key)) {
+                oldProperties[key] = System.getProperty(key)
+            }
+        }
+        overrides.overrideProperties()
+    }
+
+    override fun close() {
+        // restore the backed up properties
+        oldProperties.overrideProperties()
+        oldProperties.clear()
+    }
+
+    private fun Map<String, String?>.overrideProperties() {
+        for ((key, value) in this) {
+            if (value != null) {
+                System.setProperty(key, value)
+            } else {
+                System.clearProperty(key)
+            }
+        }
+    }
+}