Add mock utility methods for Glide's various builder classes

PiperOrigin-RevId: 307088222

Author: sjudd

mocks/build.gradle

@@ -4,6 +4,7 @@ dependencies {
     implementation project(':library')
     implementation "androidx.annotation:annotation:${ANDROID_X_VERSION}"
     implementation "com.google.guava:guava:${GUAVA_VERSION}"
+    implementation "org.mockito:mockito-core:${MOCKITO_VERSION}"
 }
 
 android {

mocks/lint.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<lint>
+    <issue id="InvalidPackage" severity="ignore" />
+</lint>

mocks/src/main/java/com/bumptech/glide/mocks/AnswerSelf.java

@@ -0,0 +1,26 @@
+package com.bumptech.glide.mocks;
+
+import static org.mockito.Mockito.RETURNS_DEFAULTS;
+
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+
+/**
+ * Useful default when mocking {@link com.bumptech.glide.request.RequestOptions} or {@link
+ * com.bumptech.glide.RequestBuilder}.
+ *
+ * @param <T> The type of the options and/or builder.
+ */
+final class AnswerSelf<T> implements Answer<T> {
+
+  @SuppressWarnings("unchecked")
+  @Override
+  public T answer(InvocationOnMock invocation) throws Throwable {
+    Object mock = invocation.getMock();
+    if (invocation.getMethod().getReturnType().isInstance(mock)) {
+      return (T) mock;
+    } else {
+      return (T) RETURNS_DEFAULTS.answer(invocation);
+    }
+  }
+}

mocks/src/main/java/com/bumptech/glide/mocks/MockGlideBuilders.java

@@ -0,0 +1,41 @@
+package com.bumptech.glide.mocks;
+
+import static org.mockito.Mockito.mock;
+
+import com.bumptech.glide.RequestBuilder;
+import com.bumptech.glide.request.RequestOptions;
+
+/**
+ * Mocks for various builder patterns in Glide to make testing easier.
+ *
+ * <p>All methods share the same behavior. Any method on the builder that returns the builder itself
+ * will default to returning the mock rather than null. Any method on the builder that returns
+ * anything other than the builder will return Mockito's standard default return value.
+ */
+public final class MockGlideBuilders {
+
+  private MockGlideBuilders() {}
+
+  /** Creates a new {@link RequestBuilder} instance with a matching resource type. */
+  @SuppressWarnings("unchecked")
+  public static <T> RequestBuilder<T> mockRequestBuilder() {
+    return (RequestBuilder<T>) mockGlideRequest(RequestBuilder.class);
+  }
+
+  /** Creates a new instance of a generated {@code GlideRequest} class for an application. */
+  // The suppressions allow callers to get a typed class without warnings in their test code.
+  @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
+  public static <T, Y extends RequestBuilder<T>> Y mockGlideRequest(Class<?> glideRequest) {
+    return (Y) mock(glideRequest, new AnswerSelf<Y>());
+  }
+
+  /** Creates a new {@link RequestOptions} instance. */
+  public static RequestOptions mockRequestOptions() {
+    return mockGlideOptions(RequestOptions.class);
+  }
+
+  /** Creates a new instance of a generated {@code GlideOptions} class for an application. */
+  public static <T extends RequestOptions> T mockGlideOptions(Class<T> glideOptionsClass) {
+    return mock(glideOptionsClass, new AnswerSelf<T>());
+  }
+}