Add support for Powermock by making getOnlyConstructor() more lenient (filter out non-public constructors).

This is consistent with how JUnit's getOnlyConstructor() is implemented.

Fixes https://github.com/google/TestParameterInjector/issues/40

9 files changed, 136 insertions, 53 deletions

diff --git a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/PluggableTestRunner.java b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/PluggableTestRunner.java
index 5f4c061..b2a0ad8 100644
--- a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/PluggableTestRunner.java
+++ b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/PluggableTestRunner.java
@@ -316,7 +316,8 @@ abstract class PluggableTestRunner extends BlockJUnit4ClassRunner {
 
   private Object createTestForMethod(FrameworkMethod method) throws Exception {
     TestInfo testInfo = ((OverriddenFrameworkMethod) method).getTestInfo();
-    Constructor<?> constructor = getTestClass().getOnlyConstructor();
+    Constructor<?> constructor =
+        TestParameterInjectorUtils.getOnlyConstructor(getTestClass().getJavaClass());
 
     // Construct a test instance
     Object testInstance;
@@ -343,7 +344,9 @@ abstract class PluggableTestRunner extends BlockJUnit4ClassRunner {
   @Override
   protected final void validateZeroArgConstructor(List<Throwable> errorsReturned) {
     ExecutableValidationResult validationResult =
-        getTestMethodProcessors().validateConstructor(getTestClass().getOnlyConstructor());
+        getTestMethodProcessors()
+            .validateConstructor(
+                TestParameterInjectorUtils.getOnlyConstructor(getTestClass().getJavaClass()));
 
     if (validationResult.wasValidated()) {
       errorsReturned.addAll(validationResult.validationErrors());
diff --git a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessor.java b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessor.java
index 31ecf25..4132f12 100644
--- a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessor.java
+++ b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessor.java
@@ -867,7 +867,8 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
                     case FIELD: // Fall through.
                     case CLASS:
                       return getAnnotationListWithType(
-                              getOnlyConstructor(testClass).getAnnotations(),
+                              TestParameterInjectorUtils.getOnlyConstructor(testClass)
+                                  .getAnnotations(),
                               annotationTypeOrigin.annotationType())
                           .isEmpty();
                     default:
@@ -890,7 +891,7 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
     Origin origin = annotationTypeOrigin.origin();
     Class<? extends Annotation> annotationType = annotationTypeOrigin.annotationType();
     if (origin == Origin.CONSTRUCTOR_PARAMETER) {
-      Constructor<?> constructor = getOnlyConstructor(testClass);
+      Constructor<?> constructor = TestParameterInjectorUtils.getOnlyConstructor(testClass);
       List<AnnotationWithMetadata> annotations =
           getAnnotationWithMetadataListWithType(constructor, annotationType);
 
@@ -898,7 +899,8 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
         return toTestParameterValueList(annotations, origin);
       }
     } else if (origin == Origin.CONSTRUCTOR) {
-      Annotation annotation = getOnlyConstructor(testClass).getAnnotation(annotationType);
+      Annotation annotation =
+          TestParameterInjectorUtils.getOnlyConstructor(testClass).getAnnotation(annotationType);
       if (annotation != null) {
         return ImmutableList.of(
             TestParameterValueHolder.create(
@@ -1022,15 +1024,6 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
         .toList();
   }
 
-  private static Constructor<?> getOnlyConstructor(Class<?> testClass) {
-    Constructor<?>[] constructors = testClass.getDeclaredConstructors();
-    checkState(
-        constructors.length == 1,
-        "a single public constructor is required for class %s",
-        testClass);
-    return constructors[0];
-  }
-
   @Override
   public void postProcessTestInstance(Object testInstance, TestInfo testInfo) {
     TestIndexHolder testIndexHolder = testInfo.getAnnotation(TestIndexHolder.class);
diff --git a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterInjectorUtils.java b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterInjectorUtils.java
new file mode 100644
index 0000000..215719a
--- /dev/null
+++ b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParameterInjectorUtils.java
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2023 Google Inc.
+ *
+ * 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.google.testing.junit.testparameterinjector;
+
+import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.Iterables.getOnlyElement;
+
+import com.google.common.collect.ImmutableList;
+import java.lang.reflect.Constructor;
+
+/** Shared utility methods. */
+class TestParameterInjectorUtils {
+
+  /**
+   * Return the only public constructor of the given test class. If there is none, return the only
+   * constructor.
+   *
+   * <p>Normally, there should be exactly one constructor (public or other), but some frameworks
+   * introduce an extra non-public constructor (see
+   * https://github.com/google/TestParameterInjector/issues/40).
+   */
+  static Constructor<?> getOnlyConstructor(Class<?> testClass) {
+    ImmutableList<Constructor<?>> constructors = ImmutableList.copyOf(testClass.getConstructors());
+    if (constructors.isEmpty()) {
+      // There are no public constructors. This is likely a JUnit5 test, so we should take the only
+      // non-public constructor instead.
+      constructors = ImmutableList.copyOf(testClass.getDeclaredConstructors());
+    }
+    checkState(
+        constructors.size() == 1, "Expected exactly one constructor, but got %s", constructors);
+    return getOnlyElement(constructors);
+  }
+
+  private TestParameterInjectorUtils() {}
+}
diff --git a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessor.java b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessor.java
index 1a8d022..7dffc29 100644
--- a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessor.java
+++ b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessor.java
@@ -16,7 +16,6 @@ package com.google.testing.junit.testparameterinjector;
 
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.base.Verify.verify;
-import static com.google.common.collect.Iterables.getOnlyElement;
 
 import com.google.auto.value.AutoAnnotation;
 import com.google.common.base.Optional;
@@ -90,7 +89,8 @@ final class TestParametersMethodProcessor implements TestMethodProcessor {
   @Override
   public List<TestInfo> calculateTestInfos(TestInfo originalTest) {
     boolean constructorIsParameterized =
-        hasRelevantAnnotation(getOnlyConstructor(originalTest.getTestClass()));
+        hasRelevantAnnotation(
+            TestParameterInjectorUtils.getOnlyConstructor(originalTest.getTestClass()));
     boolean methodIsParameterized = hasRelevantAnnotation(originalTest.getMethod());
 
     if (!constructorIsParameterized && !methodIsParameterized) {
@@ -148,7 +148,7 @@ final class TestParametersMethodProcessor implements TestMethodProcessor {
 
   private ImmutableList<Optional<TestParametersValues>>
       getConstructorParametersOrSingleAbsentElement(Class<?> testClass) {
-    Constructor<?> constructor = getOnlyConstructor(testClass);
+    Constructor<?> constructor = TestParameterInjectorUtils.getOnlyConstructor(testClass);
     return hasRelevantAnnotation(constructor)
         ? FluentIterable.from(getConstructorParameters(constructor))
             .transform(Optional::of)
@@ -444,14 +444,6 @@ final class TestParametersMethodProcessor implements TestMethodProcessor {
             .toArray(Object.class));
   }
 
-  private static Constructor<?> getOnlyConstructor(Class<?> testClass) {
-    ImmutableList<Constructor<?>> constructors =
-        ImmutableList.copyOf(testClass.getDeclaredConstructors());
-    checkState(
-        constructors.size() == 1, "Expected exactly one constructor, but got %s", constructors);
-    return getOnlyElement(constructors);
-  }
-
   /**
    * This mechanism is a workaround to be able to store the test index in the annotation list of the
    * {@link TestInfo}, since we cannot carry other information through the test runner.
diff --git a/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessorTest.java b/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessorTest.java
index 3fff85b..df3a16b 100644
--- a/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessorTest.java
+++ b/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParameterAnnotationMethodProcessorTest.java
@@ -675,6 +675,14 @@ public class TestParameterAnnotationMethodProcessorTest {
     void test(@TestParameter boolean b) {}
   }
 
+  @ClassTestResult(Result.FAILURE)
+  public static class ErrorPackagePrivateConstructor {
+    ErrorPackagePrivateConstructor() {}
+
+    @Test
+    public void test1() {}
+  }
+
   public enum EnumA {
     A1,
     A2
@@ -829,7 +837,7 @@ public class TestParameterAnnotationMethodProcessorTest {
 
       case SUCCESS_FOR_ALL_PLACEMENTS_ONLY:
         assertThrows(
-            RuntimeException.class,
+            Exception.class,
             () ->
                 SharedTestUtilitiesJUnit4.runTestsAndGetFailures(
                     newTestRunnerWithParameterizedSupport(
@@ -838,7 +846,7 @@ public class TestParameterAnnotationMethodProcessorTest {
 
       case FAILURE:
         assertThrows(
-            RuntimeException.class,
+            Exception.class,
             () ->
                 SharedTestUtilitiesJUnit4.runTestsAndGetFailures(
                     newTestRunnerWithParameterizedSupport(
diff --git a/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessorTest.java b/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessorTest.java
index d5417e6..5628330 100644
--- a/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessorTest.java
+++ b/junit4/src/test/java/com/google/testing/junit/testparameterinjector/TestParametersMethodProcessorTest.java
@@ -494,6 +494,14 @@ public class TestParametersMethodProcessorTest {
     public void test1(TestEnum testEnum) {}
   }
 
+  @RunAsTest(failsWithMessage = "Test class should have exactly one public constructor")
+  public static class InvalidTestBecausePackagePrivateConstructor {
+    InvalidTestBecausePackagePrivateConstructor() {}
+
+    @Test
+    public void test1() {}
+  }
+
   @Parameters(name = "{0}")
   public static Collection<Object[]> parameters() {
     return Arrays.stream(TestParametersMethodProcessorTest.class.getClasses())
@@ -527,12 +535,12 @@ public class TestParametersMethodProcessorTest {
   public void test_failure() throws Exception {
     assume().that(maybeFailureMessage.isPresent()).isTrue();
 
-    IllegalStateException exception =
+    Exception exception =
         assertThrows(
-            IllegalStateException.class,
+            Exception.class,
             () -> SharedTestUtilitiesJUnit4.runTestsAndGetFailures(newTestRunner()));
 
-    assertThat(exception).hasMessageThat().isEqualTo(maybeFailureMessage.get());
+    assertThat(exception).hasMessageThat().contains(maybeFailureMessage.get());
   }
 
   private PluggableTestRunner newTestRunner() throws Exception {
diff --git a/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterAnnotationMethodProcessor.java b/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterAnnotationMethodProcessor.java
index 834a83d..5aefe21 100644
--- a/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterAnnotationMethodProcessor.java
+++ b/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterAnnotationMethodProcessor.java
@@ -867,7 +867,8 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
                     case FIELD: // Fall through.
                     case CLASS:
                       return getAnnotationListWithType(
-                              getOnlyConstructor(testClass).getAnnotations(),
+                              TestParameterInjectorUtils.getOnlyConstructor(testClass)
+                                  .getAnnotations(),
                               annotationTypeOrigin.annotationType())
                           .isEmpty();
                     default:
@@ -890,7 +891,7 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
     Origin origin = annotationTypeOrigin.origin();
     Class<? extends Annotation> annotationType = annotationTypeOrigin.annotationType();
     if (origin == Origin.CONSTRUCTOR_PARAMETER) {
-      Constructor<?> constructor = getOnlyConstructor(testClass);
+      Constructor<?> constructor = TestParameterInjectorUtils.getOnlyConstructor(testClass);
       List<AnnotationWithMetadata> annotations =
           getAnnotationWithMetadataListWithType(constructor, annotationType);
 
@@ -898,7 +899,8 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
         return toTestParameterValueList(annotations, origin);
       }
     } else if (origin == Origin.CONSTRUCTOR) {
-      Annotation annotation = getOnlyConstructor(testClass).getAnnotation(annotationType);
+      Annotation annotation =
+          TestParameterInjectorUtils.getOnlyConstructor(testClass).getAnnotation(annotationType);
       if (annotation != null) {
         return ImmutableList.of(
             TestParameterValueHolder.create(
@@ -1022,15 +1024,6 @@ final class TestParameterAnnotationMethodProcessor implements TestMethodProcesso
         .toList();
   }
 
-  private static Constructor<?> getOnlyConstructor(Class<?> testClass) {
-    Constructor<?>[] constructors = testClass.getDeclaredConstructors();
-    checkState(
-        constructors.length == 1,
-        "a single public constructor is required for class %s",
-        testClass);
-    return constructors[0];
-  }
-
   @Override
   public void postProcessTestInstance(Object testInstance, TestInfo testInfo) {
     TestIndexHolder testIndexHolder = testInfo.getAnnotation(TestIndexHolder.class);
diff --git a/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterInjectorUtils.java b/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterInjectorUtils.java
new file mode 100644
index 0000000..cd47ea1
--- /dev/null
+++ b/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParameterInjectorUtils.java
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2023 Google Inc.
+ *
+ * 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.google.testing.junit.testparameterinjector.junit5;
+
+import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.Iterables.getOnlyElement;
+
+import com.google.common.collect.ImmutableList;
+import java.lang.reflect.Constructor;
+
+/** Shared utility methods. */
+class TestParameterInjectorUtils {
+
+  /**
+   * Return the only public constructor of the given test class. If there is none, return the only
+   * constructor.
+   *
+   * <p>Normally, there should be exactly one constructor (public or other), but some frameworks
+   * introduce an extra non-public constructor (see
+   * https://github.com/google/TestParameterInjector/issues/40).
+   */
+  static Constructor<?> getOnlyConstructor(Class<?> testClass) {
+    ImmutableList<Constructor<?>> constructors = ImmutableList.copyOf(testClass.getConstructors());
+    if (constructors.isEmpty()) {
+      // There are no public constructors. This is likely a JUnit5 test, so we should take the only
+      // non-public constructor instead.
+      constructors = ImmutableList.copyOf(testClass.getDeclaredConstructors());
+    }
+    checkState(
+        constructors.size() == 1, "Expected exactly one constructor, but got %s", constructors);
+    return getOnlyElement(constructors);
+  }
+
+  private TestParameterInjectorUtils() {}
+}
diff --git a/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParametersMethodProcessor.java b/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParametersMethodProcessor.java
index 3ada177..26a1e65 100644
--- a/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParametersMethodProcessor.java
+++ b/junit5/src/main/java/com/google/testing/junit/testparameterinjector/junit5/TestParametersMethodProcessor.java
@@ -16,7 +16,6 @@ package com.google.testing.junit.testparameterinjector.junit5;
 
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.base.Verify.verify;
-import static com.google.common.collect.Iterables.getOnlyElement;
 
 import com.google.auto.value.AutoAnnotation;
 import com.google.common.base.Optional;
@@ -90,7 +89,8 @@ final class TestParametersMethodProcessor implements TestMethodProcessor {
   @Override
   public List<TestInfo> calculateTestInfos(TestInfo originalTest) {
     boolean constructorIsParameterized =
-        hasRelevantAnnotation(getOnlyConstructor(originalTest.getTestClass()));
+        hasRelevantAnnotation(
+            TestParameterInjectorUtils.getOnlyConstructor(originalTest.getTestClass()));
     boolean methodIsParameterized = hasRelevantAnnotation(originalTest.getMethod());
 
     if (!constructorIsParameterized && !methodIsParameterized) {
@@ -148,7 +148,7 @@ final class TestParametersMethodProcessor implements TestMethodProcessor {
 
   private ImmutableList<Optional<TestParametersValues>>
       getConstructorParametersOrSingleAbsentElement(Class<?> testClass) {
-    Constructor<?> constructor = getOnlyConstructor(testClass);
+    Constructor<?> constructor = TestParameterInjectorUtils.getOnlyConstructor(testClass);
     return hasRelevantAnnotation(constructor)
         ? FluentIterable.from(getConstructorParameters(constructor))
             .transform(Optional::of)
@@ -444,14 +444,6 @@ final class TestParametersMethodProcessor implements TestMethodProcessor {
             .toArray(Object.class));
   }
 
-  private static Constructor<?> getOnlyConstructor(Class<?> testClass) {
-    ImmutableList<Constructor<?>> constructors =
-        ImmutableList.copyOf(testClass.getDeclaredConstructors());
-    checkState(
-        constructors.size() == 1, "Expected exactly one constructor, but got %s", constructors);
-    return getOnlyElement(constructors);
-  }
-
   /**
    * This mechanism is a workaround to be able to store the test index in the annotation list of the
    * {@link TestInfo}, since we cannot carry other information through the test runner.