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Validating OnTextChanged Event Handling in ButterKnife

This test suite validates the OnTextChanged annotation functionality in ButterKnife, focusing on text change event handling and parameter validation. The tests verify proper binding generation for TextView text change listeners with various parameter configurations and error handling.

Test Coverage Overview

The test suite provides comprehensive coverage of OnTextChanged annotation behaviors:

Basic text change event handling without parameters
Single parameter handling with CharSequence
Multiple parameter handling (CharSequence and position indices)
Invalid parameter type validation

Edge cases include parameter validation and binding lifecycle management through the Unbinder interface.

Implementation Analysis

The testing approach utilizes compile-time verification through the ButterKnifeProcessor. Tests validate generated binding code against expected source outputs using JavaFileObjects for comparison.

Key patterns include:

Source code generation verification
Compilation result assertion
Generated binding class structure validation

Technical Details

Testing tools and configuration:

JUnit test framework
Google Testing Compile utilities
Java Source Subject Factory for compilation testing
Custom compiler options (-Xlint:-processing)
ButterKnifeProcessor for annotation processing

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases for distinct functionality
Comprehensive parameter validation
Clear test method naming
Proper cleanup through unbinding verification
Generated code structure validation

jakewharton/butterknife

butterknife-runtime/src/test/java/butterknife/OnTextChangedTest.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 OnTextChangedTest {
  @Test public void textChanged() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
        + "package test;\n"
        + "import butterknife.OnTextChanged;\n"
        + "public class Test {\n"
        + "  @OnTextChanged(1) void doStuff() {}\n"
        + "}"
    );

    JavaFileObject bindingSource = JavaFileObjects.forSourceString("test/Test_ViewBinding", ""
        + "package test;\n"
        + "import android.text.Editable;\n"
        + "import android.text.TextWatcher;\n"
        + "import android.view.View;\n"
        + "import android.widget.TextView;\n"
        + "import androidx.annotation.CallSuper;\n"
        + "import androidx.annotation.UiThread;\n"
        + "import butterknife.Unbinder;\n"
        + "import butterknife.internal.Utils;\n"
        + "import java.lang.CharSequence;\n"
        + "import java.lang.IllegalStateException;\n"
        + "import java.lang.Override;\n"
        + "public class Test_ViewBinding implements Unbinder {\n"
        + "  private Test target;\n"
        + "  private View view1;\n"
        + "  private TextWatcher view1TextWatcher;\n"
        + "  @UiThread\n"
        + "  public Test_ViewBinding(final Test target, View source) {\n"
        + "    this.target = target;\n"
        + "    View view;\n"
        + "    view = Utils.findRequiredView(source, 1, \"method 'doStuff'\");\n"
        + "    view1 = view;\n"
        + "    view1TextWatcher = new TextWatcher() {\n"
        + "      @Override\n"
        + "      public void onTextChanged(CharSequence p0, int p1, int p2, int p3) {\n"
        + "        target.doStuff();\n"
        + "      }\n"
        + "      @Override\n"
        + "      public void beforeTextChanged(CharSequence p0, int p1, int p2, int p3) {\n"
        + "      }\n"
        + "      @Override\n"
        + "      public void afterTextChanged(Editable p0) {\n"
        + "      }\n"
        + "    };\n"
        + "    ((TextView) view).addTextChangedListener(view1TextWatcher);\n"
        + "  }\n"
        + "  @Override\n"
        + "  @CallSuper\n"
        + "  public void unbind() {\n"
        + "    if (target == null) throw new IllegalStateException(\"Bindings already cleared.\");\n"
        + "    target = null;\n"
        + "    ((TextView) view1).removeTextChangedListener(view1TextWatcher);\n"
        + "    view1TextWatcher = null;\n"
        + "    view1 = null;\n"
        + "  }\n"
        + "}"
    );

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

  @Test public void textChangedWithParameter() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
            + "package test;\n"
            + "import butterknife.OnTextChanged;\n"
            + "public class Test {\n"
            + "  @OnTextChanged(1) void doStuff(CharSequence p0) {}\n"
            + "}"
    );

    JavaFileObject bindingSource = JavaFileObjects.forSourceString("test/Test_ViewBinding", ""
            + "package test;\n"
            + "import android.text.Editable;\n"
            + "import android.text.TextWatcher;\n"
            + "import android.view.View;\n"
            + "import android.widget.TextView;\n"
            + "import androidx.annotation.CallSuper;\n"
            + "import androidx.annotation.UiThread;\n"
            + "import butterknife.Unbinder;\n"
            + "import butterknife.internal.Utils;\n"
            + "import java.lang.CharSequence;\n"
            + "import java.lang.IllegalStateException;\n"
            + "import java.lang.Override;\n"
            + "public class Test_ViewBinding implements Unbinder {\n"
            + "  private Test target;\n"
            + "  private View view1;\n"
            + "  private TextWatcher view1TextWatcher;\n"
            + "  @UiThread\n"
            + "  public Test_ViewBinding(final Test target, View source) {\n"
            + "    this.target = target;\n"
            + "    View view;\n"
            + "    view = Utils.findRequiredView(source, 1, \"method 'doStuff'\");\n"
            + "    view1 = view;\n"
            + "    view1TextWatcher = new TextWatcher() {\n"
            + "      @Override\n"
            + "      public void onTextChanged(CharSequence p0, int p1, int p2, int p3) {\n"
            + "        target.doStuff(p0);\n"
            + "      }\n"
            + "      @Override\n"
            + "      public void beforeTextChanged(CharSequence p0, int p1, int p2, int p3) {\n"
            + "      }\n"
            + "      @Override\n"
            + "      public void afterTextChanged(Editable p0) {\n"
            + "      }\n"
            + "    };\n"
            + "    ((TextView) view).addTextChangedListener(view1TextWatcher);\n"
            + "  }\n"
            + "  @Override\n"
            + "  @CallSuper\n"
            + "  public void unbind() {\n"
            + "    if (target == null) throw new IllegalStateException(\"Bindings already cleared.\");\n"
            + "    target = null;\n"
            + "    ((TextView) view1).removeTextChangedListener(view1TextWatcher);\n"
            + "    view1TextWatcher = null;\n"
            + "    view1 = null;\n"
            + "  }\n"
            + "}"
    );

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

  @Test public void textChangedWithParameters() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
            + "package test;\n"
            + "import butterknife.OnTextChanged;\n"
            + "public class Test {\n"
            + "  @OnTextChanged(1) void doStuff(CharSequence p0, int p1, int p2, int p3) {}\n"
            + "}"
    );

    JavaFileObject bindingSource = JavaFileObjects.forSourceString("test/Test_ViewBinding", ""
            + "package test;\n"
            + "import android.text.Editable;\n"
            + "import android.text.TextWatcher;\n"
            + "import android.view.View;\n"
            + "import android.widget.TextView;\n"
            + "import androidx.annotation.CallSuper;\n"
            + "import androidx.annotation.UiThread;\n"
            + "import butterknife.Unbinder;\n"
            + "import butterknife.internal.Utils;\n"
            + "import java.lang.CharSequence;\n"
            + "import java.lang.IllegalStateException;\n"
            + "import java.lang.Override;\n"
            + "public class Test_ViewBinding implements Unbinder {\n"
            + "  private Test target;\n"
            + "  private View view1;\n"
            + "  private TextWatcher view1TextWatcher;\n"
            + "  @UiThread\n"
            + "  public Test_ViewBinding(final Test target, View source) {\n"
            + "    this.target = target;\n"
            + "    View view;\n"
            + "    view = Utils.findRequiredView(source, 1, \"method 'doStuff'\");\n"
            + "    view1 = view;\n"
            + "    view1TextWatcher = new TextWatcher() {\n"
            + "      @Override\n"
            + "      public void onTextChanged(CharSequence p0, int p1, int p2, int p3) {\n"
            + "        target.doStuff(p0, p1, p2, p3);\n"
            + "      }\n"
            + "      @Override\n"
            + "      public void beforeTextChanged(CharSequence p0, int p1, int p2, int p3) {\n"
            + "      }\n"
            + "      @Override\n"
            + "      public void afterTextChanged(Editable p0) {\n"
            + "      }\n"
            + "    };\n"
            + "    ((TextView) view).addTextChangedListener(view1TextWatcher);\n"
            + "  }\n"
            + "  @Override\n"
            + "  @CallSuper\n"
            + "  public void unbind() {\n"
            + "    if (target == null) throw new IllegalStateException(\"Bindings already cleared.\");\n"
            + "    target = null;\n"
            + "    ((TextView) view1).removeTextChangedListener(view1TextWatcher);\n"
            + "    view1TextWatcher = null;\n"
            + "    view1 = null;\n"
            + "  }\n"
            + "}"
    );

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

  @Test public void textChangedWithWrongParameter() {
    JavaFileObject source = JavaFileObjects.forSourceString("test.Test", ""
            + "package test;\n"
            + "import butterknife.OnTextChanged;\n"
            + "public class Test {\n"
            + "  @OnTextChanged(1) void doStuff(String p0, int p1, int p2, int p3) {}\n"
            + "}"
    );

    assertAbout(javaSource()).that(source)
            .withCompilerOptions("-Xlint:-processing")
            .processedWith(new ButterKnifeProcessor())
            .failsToCompile();
  }

}