Avoid mocking java.lang.Runtime

PiperOrigin-RevId: 725357255

Author: Material Design Team

catalog/java/io/material/catalog/feature/MemoryView.java

@@ -28,6 +28,7 @@
 import android.text.format.Formatter;
 import android.util.AttributeSet;
 import android.util.TypedValue;
+import androidx.annotation.NonNull;
 import com.google.common.collect.EvictingQueue;
 import java.util.Queue;
 
@@ -129,7 +130,16 @@ protected void onAttachedToWindow() {
     paint.setColor(colorPrimary);
   }
 
-  public void refreshMemStats(Runtime runtime) {
+  /** A wrapper around {@link Runtime} to allow mocking by tests. */
+  interface RuntimeWrapper {
+    long maxMemory();
+
+    long totalMemory();
+
+    long freeMemory();
+  }
+
+  public void refreshMemStats(@NonNull RuntimeWrapper runtime) {
     maxMemoryInBytes = runtime.maxMemory();
     long availableMemInBytes = maxMemoryInBytes - (runtime.totalMemory() - runtime.freeMemory());
     long usedMemInBytes = maxMemoryInBytes - availableMemInBytes;

catalog/test/javatests/io/material/catalog/feature/MemoryViewTest.java

@@ -45,7 +45,7 @@ public class MemoryViewTest {
 
   private static final int BYTES_IN_MB = 1024 * 1024;
   private MemoryView memoryView;
-  private Runtime runtime;
+  private MemoryView.RuntimeWrapper runtime;
 
   @Before
   public void createAndMeasureMemoryView() {
@@ -60,7 +60,7 @@ public void createAndMeasureMemoryView() {
 
   @Before
   public void setUpRuntime() {
-    runtime = mock(Runtime.class);
+    runtime = mock(MemoryView.RuntimeWrapper.class);
     when(runtime.maxMemory()).thenReturn(100L * BYTES_IN_MB);
     when(runtime.totalMemory()).thenReturn(100L * BYTES_IN_MB);
     when(runtime.freeMemory()).thenReturn(75L * BYTES_IN_MB);