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/*
* Copyright (C) 2019 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 libcore.junit.util;
import static org.junit.Assert.fail;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Method;
import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;
/**
* Allows tests to specify the target SDK version that they want to run as.
*
* <p>To use add the following to the test class. It will only change the behavior of a test method
* if it is annotated with {@link TargetSdkVersion}.
*
* <pre>
* @Rule
* public TestRule switchTargetSdkVersionRule = SwitchTargetSdkVersionRule.getInstance();
* </pre>
*
* <p>Each test method that needs to run with a specific target SDK version needs to be annotated
* with {@link TargetSdkVersion} specifying the required SDK version. e.g.
*
* <pre>
* @Test
* @TargetSdkVersion(23)
* public void testAsIfTargetedAtSDK23() {
* assertEquals(23, VMRuntime.getRuntime().getTargetSdkVersion());
* }
* </pre>
*
* <p>Within the body of the method the {@code VMRuntime.getTargetSdkVersion()} will be set to the
* value specified in the annotation.
*
* <p>If used on a platform that does not support the {@code dalvik.system.VMRuntime} class then any
* test annotated with {@link TargetSdkVersion} will fail with a message explaining that it is not
* supported.
*/
public abstract class SwitchTargetSdkVersionRule implements TestRule {
private static final TestRule INSTANCE;
private static final String VMRUNTIME = "dalvik.system.VMRuntime";
// Use reflection so that this rule can compile and run against RI core libraries.
static {
TestRule rule;
try {
// Assume that VMRuntime is supported and create a rule instance that will use it.
rule = new SwitchVMRuntimeUsingReflection();
} catch (ClassNotFoundException | NoSuchMethodException e) {
// VMRuntime is not supported.
rule = new VMRuntimeNotSupported();
}
INSTANCE = rule;
}
public static TestRule getInstance() {
return INSTANCE;
}
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface TargetSdkVersion {
int value();
}
private SwitchTargetSdkVersionRule() {
}
@Override
public Statement apply(final Statement statement, Description description) {
TargetSdkVersion targetSdkVersion = description.getAnnotation(TargetSdkVersion.class);
if (targetSdkVersion == null) {
return statement;
}
return createStatement(statement, targetSdkVersion.value());
}
/**
* Create the {@link Statement} that will be run for the specific {@code targetSdkVersion}.
*
* @param statement the {@link Statement} encapsulating the test method.
* @param targetSdkVersion the target SDK version to use within the body of the test.
* @return the created {@link Statement}.
*/
protected abstract Statement createStatement(Statement statement, int targetSdkVersion);
/**
* Switch the value of {@code VMRuntime.getTargetSdkVersion()} for tests annotated with
* {@link TargetSdkVersion}.
*
* <p>Uses reflection so this class can compile and run on OpenJDK.
*/
private static class SwitchVMRuntimeUsingReflection extends SwitchTargetSdkVersionRule {
private final Method runtimeInstanceGetter;
private final Method targetSdkVersionGetter;
private final Method targetSdkVersionSetter;
private SwitchVMRuntimeUsingReflection() throws ClassNotFoundException, NoSuchMethodException {
ClassLoader classLoader = ClassLoader.getSystemClassLoader();
Class<?> runtimeClass = classLoader.loadClass(VMRUNTIME);
this.runtimeInstanceGetter = runtimeClass.getMethod("getRuntime");
this.targetSdkVersionGetter = runtimeClass.getMethod("getTargetSdkVersion");
this.targetSdkVersionSetter = runtimeClass.getMethod("setTargetSdkVersion", int.class);
}
@Override
protected Statement createStatement(Statement statement, int targetSdkVersion) {
return new Statement() {
@Override
public void evaluate() throws Throwable {
Object runtime = runtimeInstanceGetter.invoke(null);
int oldTargetSdkVersion = (int) targetSdkVersionGetter.invoke(runtime);
targetSdkVersionSetter.invoke(runtime, targetSdkVersion);
try {
statement.evaluate();
} finally {
targetSdkVersionSetter.invoke(runtime, oldTargetSdkVersion);
}
}
};
}
}
/**
* VMRuntime is not supported on this platform so fail all tests that target a specific SDK
* version
*/
private static class VMRuntimeNotSupported extends SwitchTargetSdkVersionRule {
@Override
protected Statement createStatement(Statement statement, int targetSdkVersion) {
return new Statement() {
@Override
public void evaluate() {
fail("Targeting SDK version not supported as " + VMRUNTIME + " is not supported");
}
};
}
}
}
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