Back to Repositories

Testing Data URL Loading Implementation in Glide Library

This test suite validates the DataUrlLoader class in Glide, focusing on handling and decoding of data URLs for image loading. It ensures proper handling of base64 encoded images and various invalid URL scenarios.

Test Coverage Overview

The test suite provides comprehensive coverage of the DataUrlLoader functionality, including:

Valid data URL handling and decoding
Invalid URL scheme detection
Base64 decoding validation
Error handling for malformed URLs
Edge cases with different encoding types

Implementation Analysis

The testing approach utilizes JUnit and Robolectric frameworks for Android environment simulation. The implementation employs mock objects through Mockito and follows a structured setup-execute-verify pattern. Each test case isolates specific functionality using clear input/output validation.

Technical Details

Testing tools and configuration:

JUnit 4 test framework
Robolectric for Android runtime simulation
Mockito for dependency mocking
Base64 encoding/decoding utilities
Custom callback implementation for async operations

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Proper test isolation and setup using @Before
Comprehensive error case coverage
Clear test method naming conventions
Efficient use of mock objects
Proper validation of both success and failure scenarios

bumptech/glide

library/test/src/test/java/com/bumptech/glide/load/model/DataUrlLoaderTest.java

            
package com.bumptech.glide.load.model;

import static com.bumptech.glide.RobolectricConstants.ROBOLECTRIC_SDK;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;

import android.util.Base64;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.bumptech.glide.Priority;
import com.bumptech.glide.load.Options;
import com.bumptech.glide.load.data.DataFetcher;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.robolectric.RobolectricTestRunner;
import org.robolectric.annotation.Config;

/** Tests for the {@link DataUrlLoader} class. */
@RunWith(RobolectricTestRunner.class)
@Config(sdk = ROBOLECTRIC_SDK)
public class DataUrlLoaderTest {

  // A valid base64-encoded PNG (a small "Google" logo).
  @SuppressWarnings("SpellCheckingInspection")
  private static final String VALID_PNG =
      "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAALCAYAAAAeEY8BAAADFElEQVR42mNgAAK5ig+Cii"
          + "UfSmUL3mVL5r7PE8t5M1U06027eMYLMQZKQUMDE8eyxGrOJYmdDKtCmTHkFfO/iCsUfTykUPFeASH6n1Es+3Wj"
          + "SM5rKQYqANbFcTmsC2OXYpWUKXw/R67ofQEhQ+5FecnfDnYxPJNmzAp35n8Gxv/7pTT+75PQBrFh4iq5b/lk8z"
          + "+aiue+tZDKeaPBMC8qh2leFNgB/xkYGO+Eu+ncCnZRAiuWyHv3VDzngxMui0EWPgpx6n4U4Wx7J8De86aP2blr"
          + "rgaq//fwCv8/KNT//5CU0f99okn/dwse+b9fQECx9IObQvGHMrn8D66See9eiWa9s2GYE57DMCdi6Qs3N+6HIc"
          + "4T70a4mtz2t55909u0jkE85+1Tsdx30ciWSuQ+F+VPe6kskPFc4Z6XRcp9H8t2mNxVF72Gq066K//vZe//v4cD"
          + "ru//ds7V/7dx1MoXf9gtW/zRFGLO+x7x7DeVDDOBDpgZvvSut3nWXR/LyptuxgG33Axzr7rr2TKIZb1eIpL1ej"
          + "co3mGGCWe8cRJMf7FVKO1F/y1Xww4gng6Tu+Ko7X7JTvPo/52Mm//vYMqBO2AbU/H/LUwzpQreT5LOf98PEhPL"
          + "ftslkfvGjGF6aA4QL73halh7y9XgwHVnM2G4b0G+FM549Uw440U7Q+h/eCoVSH0+GYjrrjrr2V530n16w1qdFy"
          + "R+wUYr6YKNRtH/7QzpQHzsfwMDE9gBmxl6/29hcNdu+M8G9HmCWM7bQ6I5bxPBhk0NzmGYErT0mpOe0TVHnY+X"
          + "HXRMQMKrQhkg9omkvZYUSHvZJ5T+Yh3IUoHUZ/mCqc87BdOe2UB9HXzZQWvCeTuNqPO2GgmghAROgFsZ8oCWtg"
          + "BxDNABASC1olmveEQyX/sB8SKRzJcPgbQxw0S/IoaJvksZJvsqXnLQDLhoq7n7nI3GxHOWWs4M1AQ8ic9FhdNf"
          + "7ZRKeyYCjsrUly7AqDzOQC8glP7SFWjhCVhUKiTc5xBIebaAbg4AWcyf+qxNMPXZKoGU57UCqU+KQKGCTwsAbx"
          + "BBmvLaD+cAAAAASUVORK5CYII=";

  private static final String INVALID_URL_WRONG_SCHEME1 = "test";
  private static final String INVALID_URL_WRONG_SCHEME2 = "http://google.com";
  private static final String INVALID_URL_WRONG_SCHEME3 = "data:text";
  private static final String INVALID_URL_MISSING_COMMA = "data:image/png;base64=NOT_BASE64";
  private static final String INVALID_URL_WRONG_ENCODING = "data:image/png;base32,";

  @Mock private MultiModelLoaderFactory multiFactory;
  private DataUrlLoader<String, InputStream> dataUrlLoader;
  private DataFetcher<InputStream> fetcher;
  private Options options;

  @Before
  public void setUp() {
    MockitoAnnotations.initMocks(this);
    DataUrlLoader.StreamFactory<String> factory = new DataUrlLoader.StreamFactory<>();
    options = new Options();
    dataUrlLoader = (DataUrlLoader<String, InputStream>) factory.build(multiFactory);
    fetcher = dataUrlLoader.buildLoadData(VALID_PNG, -1, -1, options).fetcher;
  }

  @Test
  public void testHandleDataUri() {
    assertTrue(dataUrlLoader.handles(VALID_PNG));
  }

  @Test
  public void testHandleFalseDataUri() {
    assertFalse(dataUrlLoader.handles(INVALID_URL_WRONG_SCHEME1));
    assertFalse(dataUrlLoader.handles(INVALID_URL_WRONG_SCHEME2));
    assertFalse(dataUrlLoader.handles(INVALID_URL_WRONG_SCHEME3));
  }

  @Test
  public void testDecode() throws IOException {
    byte[] expected =
        Base64.decode(VALID_PNG.substring(VALID_PNG.indexOf(',') + 1), Base64.DEFAULT);
    CallBack callback = new CallBack();
    fetcher.loadData(Priority.HIGH, callback);
    byte[] result = new byte[((ByteArrayInputStream) callback.data).available()];
    assertEquals(result.length, ((ByteArrayInputStream) callback.data).read(result));
    assertTrue(Arrays.equals(result, expected));
    assertNull(callback.exception);
  }

  @Test
  public void testDecodeInvalidScheme() {
    fetcher = dataUrlLoader.buildLoadData(INVALID_URL_WRONG_SCHEME1, -1, -1, options).fetcher;
    CallBack callback = new CallBack();
    fetcher.loadData(Priority.HIGH, callback);
    assertNotNull(callback.exception);
  }

  @Test
  public void testDecodeMissingComma() {
    fetcher = dataUrlLoader.buildLoadData(INVALID_URL_MISSING_COMMA, -1, -1, options).fetcher;
    CallBack callback = new CallBack();
    fetcher.loadData(Priority.HIGH, callback);
    assertNotNull(callback.exception);
  }

  @Test
  public void testDecodeWrongEncoding() {
    fetcher = dataUrlLoader.buildLoadData(INVALID_URL_WRONG_ENCODING, -1, -1, options).fetcher;
    CallBack callback = new CallBack();
    fetcher.loadData(Priority.HIGH, callback);
    assertNotNull(callback.exception);
  }

  private static final class CallBack implements DataFetcher.DataCallback<Object> {

    public Object data;
    public Exception exception;

    @Override
    public void onDataReady(@Nullable Object data) {
      this.data = data;
    }

    @Override
    public void onLoadFailed(@NonNull Exception e) {
      this.exception = e;
    }
  }
}