[JUnit] Deduplicate suggest snippets

Multiple undefined steps may generate the same suggested snippet.
Deduplicating these makes copy paste development a little bit easier.

Author: mpkorstanje

junit/src/main/java/io/cucumber/junit/JUnitReporter.java

@@ -18,6 +18,7 @@
 
 import java.net.URI;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
@@ -29,7 +30,7 @@ final class JUnitReporter {
 
     private final JUnitOptions junitOptions;
     private final EventBus bus;
-    private final Map<StepLocation, List<String>> snippetsPerStep = new TreeMap<>();
+    private final Map<StepLocation, Collection<String>> snippetsPerStep = new TreeMap<>();
     private final EventHandler<SnippetsSuggestedEvent> snippetsSuggestedEventEventHandler = this::handleSnippetSuggested;
     private List<Throwable> stepErrors;
     private TestNotifier stepNotifier;
@@ -125,7 +126,7 @@ private void handleStepResult(PickleStepTestStep testStep, Result result) {
                 );
                 break;
             case UNDEFINED:
-                List<String> snippets = snippetsPerStep.remove(
+                Collection<String> snippets = snippetsPerStep.remove(
                     new StepLocation(testStep.getUri(), testStep.getStepLine())
                 );
                 stepErrors.add(new UndefinedStepException(

junit/src/main/java/io/cucumber/junit/UndefinedStepException.java

@@ -1,52 +1,62 @@
 package io.cucumber.junit;
 
 import java.util.Collection;
-import java.util.List;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 final class UndefinedStepException extends RuntimeException {
     private static final long serialVersionUID = 1L;
 
-    UndefinedStepException(List<String> snippets) {
+    UndefinedStepException(Collection<String> snippets) {
         super(createMessage(snippets), null, false, false);
     }
 
-    private static String createMessage(List<String> snippets) {
+    private static String createMessage(Collection<String> snippets) {
         StringBuilder sb = new StringBuilder("This step is undefined");
         appendSnippets(snippets, sb);
         return sb.toString();
     }
 
-    UndefinedStepException(String stepText, List<String> snippets, Collection<List<String>> otherSnippets) {
+    UndefinedStepException(String stepText, Collection<String> snippets, Collection<Collection<String>> otherSnippets) {
         super(createMessage(stepText, snippets, otherSnippets), null, false, false);
     }
 
-    private static String createMessage(String stepText, List<String> snippets, Collection<List<String>> otherSnippets) {
+    private static String createMessage(String stepText, Collection<String> snippets, Collection<Collection<String>> otherSnippets) {
+        Set<String> otherUniqueSnippets = otherSnippets.stream()
+            .flatMap(Collection::stream)
+            .collect(Collectors.toCollection(LinkedHashSet::new));
+
+        otherUniqueSnippets.removeAll(snippets);
+
         StringBuilder sb = new StringBuilder("The step \"" + stepText + "\" is undefined");
         appendSnippets(snippets, sb);
-        appendOtherSnippets(otherSnippets, sb);
+        appendOtherSnippets(otherUniqueSnippets, sb);
         return sb.toString();
     }
 
-    private static void appendOtherSnippets(Collection<List<String>> otherSnippets, StringBuilder sb) {
+    private static void appendOtherSnippets(Collection<String> otherSnippets, StringBuilder sb) {
         if (otherSnippets.isEmpty()) {
             return;
         }
-
         sb.append("\n");
         sb.append("\n");
         sb.append("Some other steps were also undefined:\n\n");
         otherSnippets.forEach(snippet -> {
-            sb.append(String.join("\n", snippet));
+            sb.append(snippet);
             sb.append("\n");
         });
     }
 
-    private static void appendSnippets(List<String> snippets, StringBuilder sb) {
+    private static void appendSnippets(Collection<String> snippets, StringBuilder sb) {
         if (snippets.isEmpty()) {
             return;
         }
         sb.append(". You can implement it using the snippet(s) below:\n\n");
-        sb.append(String.join("\n", snippets));
+        snippets.forEach(snippet -> {
+            sb.append(snippet);
+            sb.append("\n");
+        });
     }
 
 }

junit/src/test/java/io/cucumber/junit/JUnitReporterWithStepNotificationsTest.java

@@ -252,7 +252,7 @@ void test_step_undefined_fires_assumption_failed_and_test_finished_for_undefined
         assertThat(pickleFailure.getException().getMessage(), is("" +
             "The step \"step name\" is undefined. You can implement it using the snippet(s) below:\n" +
             "\n" +
-            "some snippet"
+            "some snippet\n"
         ));
     }
 
@@ -290,7 +290,7 @@ void test_step_undefined_fires_test_failure_and_test_finished_for_undefined_step
         assertThat(pickleFailure.getException().getMessage(), is("" +
             "The step \"step name\" is undefined. You can implement it using the snippet(s) below:\n" +
             "\n" +
-            "some snippet"
+            "some snippet\n"
         ));
     }
 

junit/src/test/java/io/cucumber/junit/UndefinedStepExceptionTest.java

@@ -0,0 +1,68 @@
+package io.cucumber.junit;
+
+import org.junit.jupiter.api.Test;
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+class UndefinedStepExceptionTest {
+
+    @Test
+    void should_generate_a_message_for_a_single_snippet() {
+        UndefinedStepException exception = new UndefinedStepException(singletonList("snippet"));
+        assertThat(exception.getMessage(), is("" +
+            "This step is undefined. You can implement it using the snippet(s) below:\n" +
+            "\n" +
+            "snippet\n"
+        ));
+    }
+
+    @Test
+    void should_generate_a_message_for_step_without_additional_snippets() {
+        UndefinedStepException exception = new UndefinedStepException(
+            "step text",
+            singletonList("snippet"),
+            emptyList()
+        );
+        assertThat(exception.getMessage(), is("" +
+            "The step \"step text\" is undefined. You can implement it using the snippet(s) below:\n" +
+            "\n" +
+            "snippet\n"
+        ));
+    }
+
+    @Test
+    void should_generate_a_message_for_step_with_additional_snippets() {
+        UndefinedStepException exception = new UndefinedStepException(
+            "step text",
+            singletonList("snippet"),
+            singletonList(singletonList("additional snippet"))
+        );
+        assertThat(exception.getMessage(), is("" +
+            "The step \"step text\" is undefined. You can implement it using the snippet(s) below:\n" +
+            "\n" +
+            "snippet\n" +
+            "\n" +
+            "\n" +
+            "Some other steps were also undefined:\n" +
+            "\n" +
+            "additional snippet\n"
+        ));
+    }
+
+    @Test
+    void should_generate_a_message_for_step_with_additional_duplicated_snippets() {
+        UndefinedStepException exception = new UndefinedStepException(
+            "step text",
+            singletonList("snippet"),
+            singletonList(singletonList("snippet"))
+        );
+        assertThat(exception.getMessage(), is("" +
+            "The step \"step text\" is undefined. You can implement it using the snippet(s) below:\n" +
+            "\n" +
+            "snippet\n"
+        ));
+    }
+}