Disable NullPointerTester when com.google.common is being tested …

…under Android VMs.

As we already started to see in cl/522315614, it can't work there with type-use annotations. So, when more type-use annotations appear in cl/522310996, we'd see more failures.

`NullPointerTester` will continue to run when guava-android is tested _under a JRE_, including in our open-source tests. All that this CL affects is the additional Android-emulator tests that we run on Google infrastructure. And while it's _nice_ to run all our tests under an emulator, their _primary_ purpose is to check for usages of APIs that aren't available under old versions of Android, not to look for differences in null-handling behavior between Android and JRE (which is possible but relatively unlikely).

A more principled approach would be to edit every test that _uses_ `NullPointerTester` to skip the test under Android VMs. However, this would require editing 100+ files. And it would actually require editing even _more_: In every package that we define a `PackageSanityTests` class, `NullPointerTester` runs automatically on every class `Foo` in the package _unless_ `AbstractPackageSanityTests` finds that we've defined a method like `FooTest.testNulls()`. Thus, we'd likely have to define dozens more such methods. And those new methods may be not completely trivial in some cases, if I'm remembering how much `PackageSanityTests` does automatically (to, e.g., construct instances of the class to test against). Finally, if it helps, we did something similar to silently disable `SerializableTester` under GWT way back in cl/25672151, though I'm not sure I'd stand by that one today, since we could have modified _that_ class's users to skip the testing under GWT more easily :)

In a fun twist, we have to keep the `@AndroidIncompatible` annotations in `ClassSanityTesterTest` and `NullPointerTesterTest`:
- Before, those tests failed because they didn't see type-use `@Nullable` annotations and thus tried to pass `null` where it wasn't valid.
- Now, those tests fail because they try to make `NullPointerTester` fail on badly annotated classes, but it doesn't fail because it's doesn't run at all!

RELNOTES=n/a
PiperOrigin-RevId: 524904788

android/guava-testlib/src/com/google/common/testing/NullPointerTester.java

@@ -349,6 +349,13 @@ public int hashCode() {
    */
   private void testParameter(
       Object instance, Invokable<?, ?> invokable, int paramIndex, Class<?> testedClass) {
+    /*
+     * com.google.common is starting to rely on type-use annotations, which aren't visible under
+     * Android VMs. So we skip testing there.
+     */
+    if (isAndroid() && Reflection.getPackageName(testedClass).startsWith("com.google.common")) {
+      return;
+    }
     if (isPrimitiveOrNullable(invokable.getParameters().get(paramIndex))) {
       return; // there's nothing to test
     }
@@ -654,4 +661,9 @@ boolean isNullable(Parameter param) {
 
     abstract boolean isNullable(Parameter param);
   }
+
+  private static boolean isAndroid() {
+    // Arguably it would make more sense to test "can we see type-use annotations" directly....
+    return System.getProperty("java.runtime.name").contains("Android");
+  }
 }

android/guava-testlib/test/com/google/common/testing/ClassSanityTesterTest.java

@@ -43,7 +43,7 @@
  *
  * @author Ben Yu
  */
-@AndroidIncompatible // Android doesn't support the type-use annotations it needs
+@AndroidIncompatible // NullPointerTester refuses to run for c.g.c under Android
 public class ClassSanityTesterTest extends TestCase {
 
   private final ClassSanityTester tester = new ClassSanityTester();

android/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java

@@ -56,7 +56,7 @@
  * @author Mick Killianey
  */
 @SuppressWarnings("CheckReturnValue")
-@AndroidIncompatible // Android doesn't support the type-use annotations it needs
+@AndroidIncompatible // NullPointerTester refuses to run for c.g.c under Android
 public class NullPointerTesterTest extends TestCase {
 
   /** Non-NPE RuntimeException. */

guava-testlib/src/com/google/common/testing/NullPointerTester.java

@@ -349,6 +349,13 @@ public int hashCode() {
    */
   private void testParameter(
       Object instance, Invokable<?, ?> invokable, int paramIndex, Class<?> testedClass) {
+    /*
+     * com.google.common is starting to rely on type-use annotations, which aren't visible under
+     * Android VMs. So we skip testing there.
+     */
+    if (isAndroid() && Reflection.getPackageName(testedClass).startsWith("com.google.common")) {
+      return;
+    }
     if (isPrimitiveOrNullable(invokable.getParameters().get(paramIndex))) {
       return; // there's nothing to test
     }
@@ -654,4 +661,9 @@ boolean isNullable(Parameter param) {
 
     abstract boolean isNullable(Parameter param);
   }
+
+  private static boolean isAndroid() {
+    // Arguably it would make more sense to test "can we see type-use annotations" directly....
+    return System.getProperty("java.runtime.name").contains("Android");
+  }
 }

guava-testlib/test/com/google/common/testing/ClassSanityTesterTest.java

@@ -45,7 +45,7 @@
  *
  * @author Ben Yu
  */
-@AndroidIncompatible // Android doesn't support the type-use annotations it needs
+@AndroidIncompatible // NullPointerTester refuses to run for c.g.c under Android
 public class ClassSanityTesterTest extends TestCase {
 
   private final ClassSanityTester tester = new ClassSanityTester();

guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java

@@ -56,7 +56,7 @@
  * @author Mick Killianey
  */
 @SuppressWarnings("CheckReturnValue")
-@AndroidIncompatible // Android doesn't support the type-use annotations it needs
+@AndroidIncompatible // NullPointerTester refuses to run for c.g.c under Android
 public class NullPointerTesterTest extends TestCase {
 
   /** Non-NPE RuntimeException. */