JUnit4 test for BandwidthThrottlingExporter

Ref: Add ability to throttle exports when reading from disk. open-telemetry#638

core/src/test/java/io/opentelemetry/android/export/BandwidthThrottlingExporterTest.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.opentelemetry.android;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+
+import android.util.Log;
+import io.opentelemetry.sdk.common.CompletableResultCode;
+import io.opentelemetry.sdk.trace.data.SpanData;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.function.Function;
+import org.junit.Before;
+import org.junit.Test;
+
+public class BandwidthThrottlingExporterTest {
+
+    private SpanExporter mockDelegate; // Mocked SpanExporter to simulate the delegate
+    private Function<SpanData, String> mockCategoryFunction; // Mocked category function
+    private BandwidthThrottlingExporter exporter; // Instance of the BandwidthThrottlingExporter
+
+    @Before
+    public void setUp() {
+        // Initialize the mocked delegate and category function
+        mockDelegate = mock(SpanExporter.class);
+        mockCategoryFunction = mock(Function.class);
+
+        // Create an instance of BandwidthThrottlingExporter with a max limit of 1 KB/s and a
+        // 1-second window
+        exporter =
+                BandwidthThrottlingExporter.newBuilder(mockDelegate)
+                        .maxBytesPerSecond(1024) // 1 KB/s
+                        .timeWindow(Duration.ofSeconds(1)) // 1 second
+                        .build();
+    }
+
+    @Test
+    public void testExportWithinLimit() {
+        // Create a mock SpanData object
+        SpanData spanData = mock(SpanData.class);
+        when(spanData.getAttributes())
+                .thenReturn(Collections.singletonMap("key", "value")); // Simulate attributes
+
+        // Simulate the export of a single span
+        CompletableResultCode result = exporter.export(Collections.singletonList(spanData));
+
+        // Verify that the delegate's export method was called
+        verify(mockDelegate).export(anyList());
+        assertTrue(result.isSuccess()); // Ensure the export was successful
+    }
+
+    @Test
+    public void testExportExceedingLimit() {
+        // Create two mock SpanData objects
+        SpanData spanData1 = mock(SpanData.class);
+        SpanData spanData2 = mock(SpanData.class);
+        when(spanData1.getAttributes())
+                .thenReturn(Collections.singletonMap("key1", "value1")); // Simulate attributes
+        when(spanData2.getAttributes())
+                .thenReturn(Collections.singletonMap("key2", "value2")); // Simulate attributes
+
+        // Simulate exporting spans that exceed the limit
+        CompletableResultCode result = exporter.export(Arrays.asList(spanData1, spanData2));
+
+        // Verify that the delegate's export method was called only once
+        verify(mockDelegate, times(1)).export(anyList());
+
+        // Ensure the result is successful
+        assertTrue(result.isSuccess());
+    }
+
+    @Test
+    public void testExportWithDifferentCategories() {
+        // Create two mock SpanData objects with different attributes
+        SpanData spanData1 = mock(SpanData.class);
+        SpanData spanData2 = mock(SpanData.class);
+        when(spanData1.getAttributes()).thenReturn(Collections.singletonMap("key1", "value1"));
+        when(spanData2.getAttributes()).thenReturn(Collections.singletonMap("key2", "value2"));
+
+        // Simulate exporting both spans
+        CompletableResultCode result = exporter.export(Arrays.asList(spanData1, spanData2));
+
+        // Verify that the delegate's export method was called
+        verify(mockDelegate).export(anyList());
+
+        // Ensure the result is successful
+        assertTrue(result.isSuccess());
+    }
+
+    @Test
+    public void testThrottlingLogMessage() {
+        // Create a mock SpanData object that exceeds the limit
+        SpanData spanData = mock(SpanData.class);
+        when(spanData.getAttributes()).thenReturn(Collections.singletonMap("key", "value"));
+
+        // Export the span multiple times to exceed the limit
+        exporter.export(Collections.singletonList(spanData));
+        exporter.export(Collections.singletonList(spanData)); // This should be throttled
+
+        // Capture the log output
+        // Note: In a real test, you might want to use a logging framework that allows capturing
+        // logs
+        // Here we just verify that the log message is generated
+        // This is a placeholder as capturing logs in unit tests can be complex
+        Log.d("BandwidthThrottlingExporter", "Throttled span: " + spanData.getName());
+    }
+}