1 files changed, 76 insertions, 0 deletions
diff --git a/junit4/src/main/java/com/google/testing/junit/testparameterinjector/GenericParameterContext.java b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/GenericParameterContext.java
new file mode 100644
index 0000000..f2a8c73
--- /dev/null
+++ b/junit4/src/main/java/com/google/testing/junit/testparameterinjector/GenericParameterContext.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2024 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.collect.Iterables.getOnlyElement;
+
+import com.google.common.base.Joiner;
+import com.google.common.collect.FluentIterable;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Ordering;
+import java.lang.annotation.Annotation;
+import java.util.NoSuchElementException;
+
+/** A value class that contains extra information about the context of a field or parameter. */
+final class GenericParameterContext {
+
+  private final ImmutableList<Annotation> annotationsOnParameter;
+  private final Class<?> testClass;
+
+  GenericParameterContext(ImmutableList<Annotation> annotationsOnParameter, Class<?> testClass) {
+    this.annotationsOnParameter = annotationsOnParameter;
+    this.testClass = testClass;
+  }
+
+  /**
+   * Returns the only annotation with the given type on the field or parameter.
+   *
+   * @throws NoSuchElementException if this there is no annotation with the given type
+   * @throws IllegalArgumentException if there are multiple annotations with the given type
+   */
+  @SuppressWarnings("unchecked") // Safe because of the filter operation
+  <A extends Annotation> A getAnnotation(Class<A> annotationType) {
+    return (A)
+        getOnlyElement(
+            FluentIterable.from(annotationsOnParameter)
+                .filter(annotation -> annotation.annotationType().equals(annotationType))
+                .toList());
+  }
+
+  // TODO: b/317524353 - Add support for repeated annotations
+
+  /** The class that contains the test that is currently being run. */
+  Class<?> testClass() {
+    return testClass;
+  }
+
+  /** A list of all annotations on the field or parameter. */
+  ImmutableList<Annotation> annotationsOnParameter() {
+    return annotationsOnParameter;
+  }
+
+  @Override
+  public String toString() {
+    return String.format(
+        "context(annotationsOnParameter=[%s],testClass=%s)",
+        FluentIterable.from(
+                ImmutableList.sortedCopyOf(
+                    Ordering.natural().onResultOf(Annotation::toString), annotationsOnParameter))
+            .transform(
+                annotation -> String.format("@%s", annotation.annotationType().getSimpleName()))
+            .join(Joiner.on(',')),
+        testClass().getSimpleName());
+  }
+}