support to specify a test name formatter on @dataProvider annotation (#…

…101)

Signed-off-by: Andreas Schmid <service@aaschmid.de>

junit-jupiter/src/integTest/java/com/tngtech/test/junit/dataprovider/FormatAcceptanceTest.java

@@ -2,17 +2,50 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+import java.lang.reflect.Method;
+import java.util.List;
+
 import org.junit.jupiter.api.TestInfo;
 import org.junit.jupiter.api.TestTemplate;
 import org.junit.jupiter.api.extension.ExtendWith;
 
 import com.tngtech.junit.dataprovider.DataProvider;
 import com.tngtech.junit.dataprovider.UseDataProvider;
 import com.tngtech.junit.dataprovider.UseDataProviderExtension;
+import com.tngtech.junit.dataprovider.format.DataProviderTestNameFormatter;
 
 @ExtendWith(UseDataProviderExtension.class)
 class FormatAcceptanceTest {
 
+    static class PlusTestNameFormatter implements DataProviderTestNameFormatter {
+        @Override
+        public String format(Method testMethod, int invocationIndex, List<Object> arguments) {
+            return String.format("%s: %2d + %2d = %2d", testMethod.getName(), arguments.get(0), arguments.get(1),
+                    arguments.get(2));
+        }
+    }
+
+    @DataProvider(format = "%a[0] * %a[1] == %a[2]", formatter = PlusTestNameFormatter.class)
+    static Object[][] dataProviderPlus() {
+        // @formatter:off
+        return new Object[][] {
+            {  0,  0,  0 },
+            { -1,  0, -1 },
+            {  0,  1,  1 },
+            {  1,  1,  2 },
+            {  1, -1,  0 },
+            { -1, -1, -2 },
+        };
+        // @formatter:on
+    }
+
+    @TestTemplate
+    @UseDataProvider
+    void testPlus(int a, int b, int expected) {
+        // Expect:
+        assertThat(a + b).isEqualTo(expected);
+    }
+
     @DataProvider(format = "%a[0] * %a[1] == %a[2]")
     static Object[][] dataProviderMultiply() {
         // @formatter:off

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/DataProvider.java

@@ -12,6 +12,8 @@
 import com.tngtech.junit.dataprovider.convert.ObjectArrayConverter;
 import com.tngtech.junit.dataprovider.convert.SingleArgConverter;
 import com.tngtech.junit.dataprovider.convert.StringConverter;
+import com.tngtech.junit.dataprovider.format.DataProviderPlaceholderFormatter;
+import com.tngtech.junit.dataprovider.format.DataProviderTestNameFormatter;
 
 /**
  * Mark a method as a dataprovider used by a test method or use it directly at the test method and provide data via {@link #value()}
@@ -199,6 +201,14 @@
      */
     String format() default DEFAULT_FORMAT;
 
+    /**
+     * Formatter to be used to generate test method description. The placeholder approach which formats according to
+     * {@link #format()} is used by default.
+     *
+     * @return a formatter used to generate test names.
+     */
+    Class<? extends DataProviderTestNameFormatter> formatter() default DataProviderPlaceholderFormatter.class;
+
     /**
      * @return a custom converter converting {@link Object}{@code []} data to proper arguments
      * @see ObjectArrayConverter

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/DataProviderExtension.java

@@ -28,6 +28,6 @@ protected ConverterContext getConverterContext(DataProvider dataProvider) {
 
     @Override
     protected DisplayNameContext getDisplayNameContext(DataProvider dataProvider) {
-        return new DisplayNameContext(dataProvider.format(), getDefaultPlaceholders());
+        return new DisplayNameContext(dataProvider.formatter(), dataProvider.format(), getDefaultPlaceholders());
     }
 }

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/DataProviderInvocationContext.java

@@ -9,9 +9,9 @@
 
 import org.junit.jupiter.api.extension.Extension;
 import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
+import org.junit.platform.commons.util.ReflectionUtils;
 
-import com.tngtech.junit.dataprovider.placeholder.BasePlaceholder;
-import com.tngtech.junit.dataprovider.placeholder.ReplacementData;
+import com.tngtech.junit.dataprovider.format.DataProviderPlaceholderFormatter;
 
 class DataProviderInvocationContext implements TestTemplateInvocationContext {
 
@@ -27,13 +27,14 @@ class DataProviderInvocationContext implements TestTemplateInvocationContext {
 
     @Override
     public String getDisplayName(int invocationIndex) {
-        ReplacementData data = ReplacementData.of(testMethod, invocationIndex, arguments);
 
-        String result = displayNameContext.getFormat();
-        for (BasePlaceholder placeHolder : displayNameContext.getPlaceholders()) {
-            result = placeHolder.process(data, result);
+        if (displayNameContext.getFormatter() == null
+                || DataProviderPlaceholderFormatter.class.equals(displayNameContext.getFormatter())) {
+            return new DataProviderPlaceholderFormatter(displayNameContext.getFormat(),
+                    displayNameContext.getPlaceholders()).format(testMethod, invocationIndex, arguments);
         }
-        return result;
+        return ReflectionUtils.newInstance(displayNameContext.getFormatter()).format(testMethod, invocationIndex,
+                arguments);
     }
 
     @Override

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/DisplayNameContext.java

@@ -6,18 +6,30 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import com.tngtech.junit.dataprovider.format.DataProviderTestNameFormatter;
 import com.tngtech.junit.dataprovider.placeholder.BasePlaceholder;
 
 public class DisplayNameContext {
 
+    private final Class<? extends DataProviderTestNameFormatter> formatter;
     private final String format;
     private final List<? extends BasePlaceholder> placeholders;
 
     public DisplayNameContext(String format, List<? extends BasePlaceholder> placeholders) {
+        this(null, format, placeholders);
+    }
+
+    public DisplayNameContext(Class<? extends DataProviderTestNameFormatter> formatter, String format,
+            List<? extends BasePlaceholder> placeholders) {
+        this.formatter = formatter;
         this.format = checkNotNull(format, "'format' must not be null");
         this.placeholders = new ArrayList<>(checkNotNull(placeholders, "'placeholders' must not be null"));
     }
 
+    public Class<? extends DataProviderTestNameFormatter> getFormatter() {
+        return formatter;
+    }
+
     public String getFormat() {
         return format;
     }

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/UseDataProviderExtension.java

@@ -42,6 +42,6 @@ protected boolean cacheDataProviderResult(DataProvider dataProviderAnnotation) {
 
     @Override
     protected DisplayNameContext getDisplayNameContext(DataProvider dataProvider) {
-        return new DisplayNameContext(dataProvider.format(), getDefaultPlaceholders());
+        return new DisplayNameContext(dataProvider.formatter(), dataProvider.format(), getDefaultPlaceholders());
     }
 }

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/UseDataProviderInvocationContextProvider.java

@@ -23,6 +23,7 @@
 
 import com.tngtech.junit.dataprovider.convert.ConverterContext;
 import com.tngtech.junit.dataprovider.convert.DataConverter;
+import com.tngtech.junit.dataprovider.format.DataProviderTestNameFormatter;
 import com.tngtech.junit.dataprovider.resolver.DataProviderResolverContext;
 
 /**

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/format/DataProviderPlaceholderFormatter.java

@@ -0,0 +1,29 @@
+package com.tngtech.junit.dataprovider.format;
+
+import java.lang.reflect.Method;
+import java.util.List;
+
+import com.tngtech.junit.dataprovider.placeholder.BasePlaceholder;
+import com.tngtech.junit.dataprovider.placeholder.ReplacementData;
+
+public class DataProviderPlaceholderFormatter implements DataProviderTestNameFormatter {
+
+    private final String format;
+    private final List<? extends BasePlaceholder> placeholders;
+
+    public DataProviderPlaceholderFormatter(String format, List<? extends BasePlaceholder> placeholders) {
+        this.format = format;
+        this.placeholders = placeholders;
+    }
+
+    @Override
+    public String format(Method testMethod, int invocationIndex, List<Object> arguments) {
+        ReplacementData data = ReplacementData.of(testMethod, invocationIndex, arguments);
+
+        String result = format;
+        for (BasePlaceholder placeHolder : placeholders) {
+            result = placeHolder.process(data, result);
+        }
+        return result;
+    }
+}

junit-jupiter/src/main/java/com/tngtech/junit/dataprovider/format/DataProviderTestNameFormatter.java

@@ -0,0 +1,9 @@
+package com.tngtech.junit.dataprovider.format;
+
+import java.lang.reflect.Method;
+import java.util.List;
+
+public interface DataProviderTestNameFormatter {
+
+    String format(Method testMethod, int invocationIndex, List<Object> arguments);
+}