Back to Repositories

Validating Font Resource Binding Implementation in ButterKnife

This test suite validates the @BindFont annotation functionality in ButterKnife, focusing on font resource binding and typeface style handling. The tests ensure proper Android font resource integration and type safety for the binding process.

Test Coverage Overview

The test suite provides comprehensive coverage of @BindFont functionality:

Basic font resource binding for SDK 26+
Typeface style application and validation
Type safety enforcement
Error handling for invalid style values

The tests verify both successful binding scenarios and proper error reporting for invalid configurations.

Implementation Analysis

The testing approach utilizes JUnit with Google’s compile-testing framework to validate annotation processing:

Source code generation verification
Compiler option handling for SDK versioning
Generated binding class structure validation
Annotation parameter validation

Technical Details

Testing infrastructure includes:

ButterKnifeProcessor for annotation processing
JavaFileObjects for test source creation
Truth assertion framework for compile-time validation
SDK version-specific compiler options
Resource type safety checks

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases for distinct functionality
Comprehensive error condition coverage
Generated code validation
Clear test naming conventions
Proper annotation processor testing patterns

jakewharton/butterknife

butterknife-runtime/src/test/java/butterknife/BindFontTest.java

            
package butterknife;

import butterknife.compiler.ButterKnifeProcessor;
import com.google.testing.compile.JavaFileObjects;
import javax.tools.JavaFileObject;
import org.junit.Test;

import static com.google.common.truth.Truth.assertAbout;
import static com.google.testing.compile.JavaSourceSubjectFactory.javaSource;

public class BindFontTest {
  @Test public void simpleIntSdk26() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
        + "package test;\n"
        + "import android.graphics.Typeface;\n"
        + "import butterknife.BindFont;\n"
        + "public class Test {\n"
        + "  @BindFont(1) Typeface one;\n"
        + "}"
    );

    JavaFileObject bindingSource = JavaFileObjects.forSourceString("test/Test_ViewBinding", ""
        + "// Generated code from Butter Knife. Do not modify!\n"
        + "package test;\n"
        + "import android.content.Context;\n"
        + "import android.content.res.Resources;\n"
        + "import android.view.View;\n"
        + "import androidx.annotation.CallSuper;\n"
        + "import androidx.annotation.UiThread;\n"
        + "import butterknife.Unbinder;\n"
        + "import java.lang.Deprecated;\n"
        + "import java.lang.Override;\n"
        + "import java.lang.SuppressWarnings;\n"
        + "public class Test_ViewBinding implements Unbinder {\n"
        + "  /**\n"
        + "   * @deprecated Use {@link #Test_ViewBinding(Test, Context)} for direct creation.\n"
        + "   *     Only present for runtime invocation through {@code ButterKnife.bind()}.\n"
        + "   */\n"
        + "  @Deprecated\n"
        + "  @UiThread\n"
        + "  public Test_ViewBinding(Test target, View source) {\n"
        + "    this(target, source.getContext());\n"
        + "  }\n"
        + "  @UiThread\n"
        + "  @SuppressWarnings(\"ResourceType\")\n"
        + "  public Test_ViewBinding(Test target, Context context) {\n"
        + "    Resources res = context.getResources();\n"
        + "    target.one = res.getFont(1);\n"
        + "  }\n"
        + "  @Override\n"
        + "  @CallSuper\n"
        + "  public void unbind() {\n"
        + "  }\n"
        + "}"
    );

    assertAbout(javaSource()).that(source)
        .withCompilerOptions("-Xlint:-processing", "-Abutterknife.minSdk=26")
        .processedWith(new ButterKnifeProcessor())
        .compilesWithoutWarnings()
        .and()
        .generatesSources(bindingSource);
  }

  @Test public void styleSdk26() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
        + "package test;\n"
        + "import android.graphics.Typeface;\n"
        + "import butterknife.BindFont;\n"
        + "public class Test {\n"
        + "  @BindFont(value = 1, style = Typeface.BOLD) Typeface one;\n"
        + "}"
    );

    JavaFileObject bindingSource = JavaFileObjects.forSourceString("test/Test_ViewBinding", ""
        + "// Generated code from Butter Knife. Do not modify!\n"
        + "package test;\n"
        + "import android.content.Context;\n"
        + "import android.content.res.Resources;\n"
        + "import android.graphics.Typeface;\n"
        + "import android.view.View;\n"
        + "import androidx.annotation.CallSuper;\n"
        + "import androidx.annotation.UiThread;\n"
        + "import butterknife.Unbinder;\n"
        + "import java.lang.Deprecated;\n"
        + "import java.lang.Override;\n"
        + "import java.lang.SuppressWarnings;\n"
        + "public class Test_ViewBinding implements Unbinder {\n"
        + "  /**\n"
        + "   * @deprecated Use {@link #Test_ViewBinding(Test, Context)} for direct creation.\n"
        + "   *     Only present for runtime invocation through {@code ButterKnife.bind()}.\n"
        + "   */\n"
        + "  @Deprecated\n"
        + "  @UiThread\n"
        + "  public Test_ViewBinding(Test target, View source) {\n"
        + "    this(target, source.getContext());\n"
        + "  }\n"
        + "  @UiThread\n"
        + "  @SuppressWarnings(\"ResourceType\")\n"
        + "  public Test_ViewBinding(Test target, Context context) {\n"
        + "    Resources res = context.getResources();\n"
        + "    target.one = Typeface.create(res.getFont(1), Typeface.BOLD);\n"
        + "  }\n"
        + "  @Override\n"
        + "  @CallSuper\n"
        + "  public void unbind() {\n"
        + "  }\n"
        + "}"
    );

    assertAbout(javaSource()).that(source)
        .withCompilerOptions("-Xlint:-processing", "-Abutterknife.minSdk=26")
        .processedWith(new ButterKnifeProcessor())
        .compilesWithoutWarnings()
        .and()
        .generatesSources(bindingSource);
  }

  @Test public void typeMustBeTypeface() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
        + "package test;\n"
        + "import butterknife.BindFont;\n"
        + "public class Test {\n"
        + "  @BindFont(1) String one;\n"
        + "}"
    );

    assertAbout(javaSource()).that(source)
        .processedWith(new ButterKnifeProcessor())
        .failsToCompile()
        .withErrorContaining("@BindFont field type must be 'Typeface'. (test.Test.one)")
        .in(source).onLine(4);
  }

  @Test public void styleMustBeValid() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
        + "package test;\n"
        + "import android.graphics.Typeface;\n"
        + "import butterknife.BindFont;\n"
        + "public class Test {\n"
        + "  @BindFont(value = 1, style = 5) Typeface one;\n"
        + "}"
    );

    assertAbout(javaSource()).that(source)
        .processedWith(new ButterKnifeProcessor())
        .failsToCompile()
        .withErrorContaining(
            "@BindFont style must be NORMAL, BOLD, ITALIC, or BOLD_ITALIC. (test.Test.one)")
        .in(source).onLine(5);
  }
}