Workaround for arity mismatch on Groovy. Need an explicitly empty list of closure parameters. Closes #297.

Author: aslakhellesoy

History.md

@@ -1,5 +1,6 @@
 ## [Git master](https://github.com/cucumber/cucumber-jvm/compare/v1.0.1...master)
 
+* [Groovy] Arity mismatch can be avoided by explicitly declaring an empty list of closure parameters. ([#297](https://github.com/cucumber/cucumber-jvm/issues/297) Aslak Hellesøy)
 * [Core] Added DataTable.toTable(List<?> other) for creating a new table. Handy for printing a table when diffing isn't helpful. (Aslak Hellesøy)
 
 ## [1.0.2](https://github.com/cucumber/cucumber-jvm/compare/v1.0.1...v1.0.2)

core/src/main/java/cucumber/runtime/StepDefinitionMatch.java

@@ -65,8 +65,7 @@ private Object[] transformedArgs(List<ParameterType> parameterTypes, Step step,
         if (step.getRows() != null) argumentCount++;
         if (parameterTypes != null) {
             if (parameterTypes.size() != argumentCount) {
-                List<Argument> arguments = createArgumentsForErrorMessage(step);
-                throw new CucumberException("Arity mismatch. Declared parameters: " + parameterTypes + ". Matched arguments: " + arguments);
+                throw arityMismatch(parameterTypes, step);
             }
         } else {
             // Some backends, like ClojureBackend, don't know the arity and therefore pass in null.
@@ -116,6 +115,21 @@ private Object[] transformedArgs(List<ParameterType> parameterTypes, Step step,
         return result;
     }
 
+    private CucumberException arityMismatch(List<ParameterType> parameterTypes, Step step) {
+        List<Argument> arguments = createArgumentsForErrorMessage(step);
+        return new CucumberException(String.format(
+                "Arity mismatch: Step Definition '%s' with pattern /%s/ is declared with %s parameters%s. However, the gherkin step matched %s arguments%s. \nStep: %s%s",
+                stepDefinition.getLocation(),
+                stepDefinition.getPattern(),
+                parameterTypes.size(),
+                parameterTypes.isEmpty() ? "" : " " + parameterTypes.toString(),
+                arguments.size(),
+                arguments.isEmpty() ? "" : " " + arguments.toString(),
+                step.getKeyword(),
+                step.getName()
+        ));
+    }
+
     private List<Argument> createArgumentsForErrorMessage(Step step) {
         List<Argument> arguments = new ArrayList<Argument>(getArguments());
         if (step.getDocString() != null) {

core/src/test/java/cucumber/runtime/StepDefinitionMatchTest.java

@@ -3,7 +3,6 @@
 import cucumber.runtime.converters.LocalizedXStreams;
 import gherkin.I18n;
 import gherkin.formatter.Argument;
-import gherkin.formatter.Reporter;
 import gherkin.formatter.model.DocString;
 import gherkin.formatter.model.Step;
 import org.junit.Test;
@@ -14,6 +13,7 @@
 
 import static java.util.Arrays.asList;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -25,7 +25,6 @@ public class StepDefinitionMatchTest {
     @Test
     public void converts_numbers() throws Throwable {
         StepDefinition stepDefinition = mock(StepDefinition.class);
-        Reporter reporter = mock(Reporter.class);
         List<ParameterType> parameterTypes = asList(new ParameterType(Integer.TYPE, null));
         when(stepDefinition.getParameterTypes()).thenReturn(parameterTypes);
 
@@ -41,7 +40,6 @@ public void converts_numbers() throws Throwable {
     @Test
     public void can_have_doc_string_as_only_argument() throws Throwable {
         StepDefinition stepDefinition = mock(StepDefinition.class);
-        Reporter reporter = mock(Reporter.class);
         List<ParameterType> parameterTypes = asList(new ParameterType(String.class, null));
         when(stepDefinition.getParameterTypes()).thenReturn(parameterTypes);
 
@@ -58,7 +56,6 @@ public void can_have_doc_string_as_only_argument() throws Throwable {
     @Test
     public void can_have_doc_string_as_last_argument_among_many() throws Throwable {
         StepDefinition stepDefinition = mock(StepDefinition.class);
-        Reporter reporter = mock(Reporter.class);
         List<ParameterType> parameterTypes = asList(new ParameterType(Integer.TYPE, null), new ParameterType(String.class, null));
         when(stepDefinition.getParameterTypes()).thenReturn(parameterTypes);
 
@@ -73,15 +70,17 @@ public void can_have_doc_string_as_last_argument_among_many() throws Throwable {
     }
 
     @Test
-    public void retrieve_step_name() {
-        String theName = "name";
-
-        Step step = mock(Step.class);
-        when(step.getName()).thenReturn(theName);
-
-        StepDefinitionMatch stepDefinitionMatch = new StepDefinitionMatch(null, mock(StepDefinition.class), null, step, null);
-
-        String stepName = stepDefinitionMatch.getStepName();
-        assertEquals(theName, stepName);
+    public void throws_arity_mismatch_exception() throws Throwable {
+        Step step = new Step(null, "Given ", "I have 4 cukes in my belly", 1, null, null);
+
+        StepDefinition stepDefinition = new StubStepDefinition(new Object(), Object.class.getMethod("toString"), "some pattern");
+        StepDefinitionMatch stepDefinitionMatch = new StepDefinitionMatch(asList(new Argument(7, "3")), stepDefinition, null, step, new LocalizedXStreams(getClass().getClassLoader()));
+        try {
+            stepDefinitionMatch.runStep(new I18n("en"));
+            fail();
+        } catch(CucumberException expected) {
+            assertEquals("Arity mismatch: Step Definition 'toString' with pattern /some pattern/ is declared with 0 parameters. However, the gherkin step matched 1 arguments [3]. \n" +
+                    "Step: Given I have 4 cukes in my belly", expected.getMessage());
+        }
     }
 }

core/src/test/java/cucumber/runtime/StubStepDefinition.java

@@ -0,0 +1,50 @@
+package cucumber.runtime;
+
+import gherkin.I18n;
+import gherkin.formatter.Argument;
+import gherkin.formatter.model.Step;
+
+import java.lang.reflect.Method;
+import java.util.List;
+
+public class StubStepDefinition implements StepDefinition {
+    private final Object target;
+    private final Method method;
+    private final String pattern;
+
+    public StubStepDefinition(Object target, Method method, String pattern) {
+        this.target = target;
+        this.method = method;
+        this.pattern = pattern;
+    }
+
+    @Override
+    public List<Argument> matchedArguments(Step step) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public String getLocation() {
+        return method.getName();
+    }
+
+    @Override
+    public List<ParameterType> getParameterTypes() {
+        return ParameterType.fromMethod(method);
+    }
+
+    @Override
+    public void execute(I18n i18n, Object[] args) throws Throwable {
+        method.invoke(target, args);
+    }
+
+    @Override
+    public boolean isDefinedAt(StackTraceElement stackTraceElement) {
+        return false;
+    }
+
+    @Override
+    public String getPattern() {
+        return pattern;
+    }
+}

core/src/test/java/cucumber/table/FromDataTableTest.java

@@ -9,9 +9,9 @@
 import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
 import cucumber.DateFormat;
 import cucumber.runtime.CucumberException;
-import cucumber.runtime.ParameterType;
 import cucumber.runtime.StepDefinition;
 import cucumber.runtime.StepDefinitionMatch;
+import cucumber.runtime.StubStepDefinition;
 import cucumber.runtime.converters.LocalizedXStreams;
 import gherkin.I18n;
 import gherkin.formatter.Argument;
@@ -171,7 +171,7 @@ public void does_not_transform_to_list_of_non_generic_map() throws Throwable {
 
     private StepDefs runStepDef(Method method, List<DataTableRow> rows) throws Throwable {
         StepDefs stepDefs = new StepDefs();
-        StepDefinition stepDefinition = new DirectStepDef(stepDefs, method);
+        StepDefinition stepDefinition = new StubStepDefinition(stepDefs, method, "some pattern");
 
         Step stepWithRows = new Step(NO_COMMENTS, "Given ", "something", 10, rows, null);
 
@@ -276,43 +276,4 @@ public boolean canConvert(Class type) {
         }
     }
 
-    private class DirectStepDef implements StepDefinition {
-        private final Object target;
-        private final Method method;
-
-        public DirectStepDef(Object target, Method method) {
-            this.target = target;
-            this.method = method;
-        }
-
-        @Override
-        public List<Argument> matchedArguments(Step step) {
-            throw new UnsupportedOperationException();
-        }
-
-        @Override
-        public String getLocation() {
-            return getClass().getName();
-        }
-
-        @Override
-        public List<ParameterType> getParameterTypes() {
-            return ParameterType.fromMethod(method);
-        }
-
-        @Override
-        public void execute(I18n i18n, Object[] args) throws Throwable {
-            method.invoke(target, args);
-        }
-
-        @Override
-        public boolean isDefinedAt(StackTraceElement stackTraceElement) {
-            return false;
-        }
-
-        @Override
-        public String getPattern() {
-            throw new UnsupportedOperationException();
-        }
-    }
 }

groovy/src/test/groovy/cucumber/runtime/groovy/compiled_stepdefs.groovy

@@ -13,7 +13,7 @@ Given(~'^I have (\\d+) apples in my belly') { int apples ->
     lastAte('apples')
 }
 
-Given(~'^a big basket with cukes') {->
+Given(~'^a big basket with cukes') { ->
 }
 
 Given(~'^the following table:$') { table ->

groovy/src/test/java/cucumber/runtime/groovy/RunCukesTest.java

@@ -4,5 +4,6 @@
 import org.junit.runner.RunWith;
 
 @RunWith(Cucumber.class)
+@Cucumber.Options(tags="@focus")
 public class RunCukesTest {
 }

groovy/src/test/resources/cucumber/runtime/groovy/a_feature.feature

@@ -16,7 +16,6 @@ Feature: Cucumber Runner Rocks
       | 13 | cukes  | happy |
       |  4 | apples | tired |
 
-  @focus
   Scenario: a table
     Given the following table:
       | year | name         |

groovy/src/test/resources/cucumber/runtime/groovy/issue_297.feature

@@ -0,0 +1,4 @@
+@focus
+Feature: Issue 297
+  Scenario: Carbon Coder executes unsuccessfully
+    Given Carbon Coder is running correctly

groovy/src/test/resources/cucumber/runtime/groovy/issue_297_stepdefs.groovy

@@ -0,0 +1,6 @@
+package cucumber.runtime.groovy
+this.metaClass.mixin(cucumber.runtime.groovy.EN)
+
+// Step definitions without parameters must explicitly define an empty list of parameters.
+Given(~"Carbon Coder is running correctly\$") { ->
+}