Enable testing platform conditions

- Implement unit tests for the ByteBuddy platform conditions
- Extract the ByteBuddy platform conditions to a separate utility class
  to enable unit testing them separately. This also enables adding additional
  checks in the future without making the InlineDelegateByteBuddyMockMaker
  much more complicated.
- Added dependency at test time for junit-jupiter-params to enable writing
  parameterized unit tests.

build.gradle

@@ -96,6 +96,8 @@ dependencies {
     implementation libraries.objenesis
 
     testImplementation libraries.assertj
+    testImplementation libraries.junitJupiterApi
+    testImplementation libraries.junitJupiterParams
 
     testUtil sourceSets.test.output
 

gradle/dependencies.gradle

@@ -10,6 +10,7 @@ versions.errorprone = '2.23.0'
 
 libraries.junit4 = 'junit:junit:4.13.2'
 libraries.junitJupiterApi = "org.junit.jupiter:junit-jupiter-api:${versions.junitJupiter}"
+libraries.junitJupiterParams = "org.junit.jupiter:junit-jupiter-params:${versions.junitJupiter}"
 libraries.junitPlatformLauncher = 'org.junit.platform:junit-platform-launcher:1.10.0'
 libraries.junitJupiterEngine = "org.junit.jupiter:junit-jupiter-engine:${versions.junitJupiter}"
 libraries.junitVintageEngine = "org.junit.vintage:junit-vintage-engine:${versions.junitJupiter}"

src/main/java/org/mockito/internal/creation/bytebuddy/InlineDelegateByteBuddyMockMaker.java

@@ -207,17 +207,7 @@ class InlineDelegateByteBuddyMockMaker
     InlineDelegateByteBuddyMockMaker() {
         if (INITIALIZATION_ERROR != null) {
             String detail;
-
-            boolean isNativeAndroid = System.getProperty("java.specification.vendor", "")
-                    .toLowerCase()
-                    .contains("android");
-
-            // Termux can run any JVM, such as Oracle, but may still fail to instrument the
-            // JVM correctly, so it is worth detecting this as well.
-            boolean isTermuxAndroid = System.getProperty("java.home", "")
-                    .contains("/com.termux/");
-
-            if (isNativeAndroid || isTermuxAndroid) {
+            if (PlatformUtils.isAndroidPlatform() || PlatformUtils.isProbablyTermuxEnvironment()) {
                 detail =
                         "It appears as if you are trying to run this mock maker on Android which does not support the instrumentation API.";
             } else {

src/main/java/org/mockito/internal/creation/bytebuddy/PlatformUtils.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2023 Mockito contributors
+ * This program is made available under the terms of the MIT License.
+ */
+package org.mockito.internal.creation.bytebuddy;
+
+/**
+ * Helpers for various platform detection mechanisms related to the ByteBuddy mock maker.
+ *
+ * @author Ashley Scopes
+ */
+final class PlatformUtils {
+    private PlatformUtils() {
+        // Static-only class.
+    }
+
+    static boolean isAndroidPlatform() {
+        return System.getProperty("java.specification.vendor", "")
+                .toLowerCase()
+                .contains("android");
+    }
+
+    static boolean isProbablyTermuxEnvironment() {
+        boolean isLinux = System.getProperty("os.name", "").equalsIgnoreCase("linux");
+        boolean isInTermuxData =
+                System.getProperty("java.home", "").toLowerCase().contains("/com.termux/");
+        return isLinux && isInTermuxData;
+    }
+}

src/test/java/org/mockito/internal/creation/bytebuddy/PlatformUtilsTest.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2023 Mockito contributors
+ * This program is made available under the terms of the MIT License.
+ */
+package org.mockito.internal.creation.bytebuddy;
+
+import java.util.Properties;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.parallel.Isolated;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Ashley Scopes
+ */
+@Isolated("modifies system properties temporarily")
+class PlatformUtilsTest {
+    Properties globalProperties;
+
+    @BeforeEach
+    void setUp() {
+        globalProperties = new Properties();
+        globalProperties.putAll(System.getProperties());
+        System.getProperties().clear();
+    }
+
+    @AfterEach
+    void tearDown() {
+        System.getProperties().clear();
+        System.getProperties().putAll(globalProperties);
+    }
+
+    @CsvSource({
+        "     android,  true",
+        "     AnDrOId,  true",
+        "anythingElse, false",
+        "            , false",
+    })
+    @ParameterizedTest
+    void isAndroidPlatform_returns_expected_value(String vendor, boolean expectedResult) {
+        // Given
+        setProperty("java.specification.vendor", vendor);
+
+        // Then
+        assertThat(PlatformUtils.isAndroidPlatform()).isEqualTo(expectedResult);
+    }
+
+    @CsvSource({
+        "        linux, /data/data/com.termux/whatever,  true",
+        "        linux,    /foo/bar/com.termux/somedir,  true",
+        "        LINUX, /data/data/com.termux/whatever,  true",
+        "        Linux,    /foo/bar/com.termux/somedir,  true",
+        "Mac OS X 13.0,    /foo/bar/com.termux/somedir, false",
+        "   Windows 10,    /foo/bar/com.termux/somedir, false",
+        "         OS/2,    /foo/bar/com.termux/somedir, false",
+        "        Linux,                /usr/share/java, false",
+        "             ,                               , false",
+        "          foo,                               , false",
+        "             ,                            foo, false",
+        "        linux,                               , false",
+        "             , /data/data/com.termux/whatever, false",
+    })
+    @ParameterizedTest
+    void isAndroidPlatform_returns_expected_value(
+            String os, String javaHome, boolean expectedResult) {
+        // Given
+        setProperty("os.name", os);
+        setProperty("java.home", javaHome);
+
+        assertThat(PlatformUtils.isAndroidPlatform()).isEqualTo(expectedResult);
+    }
+
+    static void setProperty(String name, String value) {
+        if (value == null) {
+            System.clearProperty(name);
+        } else {
+            System.setProperty(name, value);
+        }
+    }
+}