Merge pull request #607 from pimterry/theory-enum-failure-messages

Theories failure messages describe enum arguments unhelpfully

src/main/java/org/junit/experimental/theories/PotentialAssignment.java

@@ -1,5 +1,7 @@
 package org.junit.experimental.theories;
 
+import static java.lang.String.format;
+
 public abstract class PotentialAssignment {
     public static class CouldNotGenerateValueException extends Exception {
         private static final long serialVersionUID = 1L;
@@ -8,24 +10,36 @@ public static class CouldNotGenerateValueException extends Exception {
     public static PotentialAssignment forValue(final String name, final Object value) {
         return new PotentialAssignment() {
             @Override
-            public Object getValue() throws CouldNotGenerateValueException {
+            public Object getValue() {
                 return value;
             }
 
             @Override
             public String toString() {
-                return String.format("[%s]", value);
+                return format("[%s]", value);
             }
 
             @Override
-            public String getDescription()
-                    throws CouldNotGenerateValueException {
-                return name;
+            public String getDescription() {
+                String valueString;
+
+                if (value == null) {
+                    valueString = "null";
+                } else {
+                    try {
+                        valueString = format("\"%s\"", value);
+                    } catch (Throwable e) {
+                        valueString = format("[toString() threw %s: %s]", 
+                                             e.getClass().getSimpleName(), e.getMessage());
+                    }
+                }
+
+                return format("%s <from %s>", valueString, name);
             }
         };
     }
 
     public abstract Object getValue() throws CouldNotGenerateValueException;
 
     public abstract String getDescription() throws CouldNotGenerateValueException;
-}
+}

src/test/java/org/junit/tests/experimental/theories/PotentialAssignmentTest.java

@@ -0,0 +1,57 @@
+package org.junit.tests.experimental.theories;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+import org.junit.experimental.theories.PotentialAssignment;
+import org.junit.experimental.theories.PotentialAssignment.CouldNotGenerateValueException;
+
+public class PotentialAssignmentTest {
+
+    @Test
+    public void shouldUseQuotedValueInDescription() throws CouldNotGenerateValueException {
+        String name = "stringDatapoint";
+        Object value = new Object() {
+            @Override
+            public String toString() {
+                return "string value";
+            }
+        };
+
+        PotentialAssignment assignment = PotentialAssignment.forValue(name, value);
+
+        assertEquals("\"string value\" <from stringDatapoint>", assignment.getDescription());
+    }
+
+    @Test
+    public void shouldNotUseQuotesForNullValueDescriptions() throws CouldNotGenerateValueException {
+        String name = "nullDatapoint";
+        Object value = null;
+
+        PotentialAssignment assignment = PotentialAssignment.forValue(name, value);
+
+        assertEquals("null <from nullDatapoint>", assignment.getDescription());
+    }
+
+    @Test
+    public void shouldIncludeFailureInDescriptionIfToStringFails() throws CouldNotGenerateValueException {
+        String name = "explodingValue";
+        Object value = new Object() {
+            @Override
+            public String toString() {
+                throw new RuntimeException("Oh no!");
+            }
+        };
+
+        PotentialAssignment assignment = PotentialAssignment.forValue(name, value);
+
+        assertEquals("[toString() threw RuntimeException: Oh no!] <from explodingValue>", assignment.getDescription());
+    }
+
+    @Test
+    public void shouldReturnGivenValue() throws CouldNotGenerateValueException {
+        Object value = new Object();
+        PotentialAssignment assignment = PotentialAssignment.forValue("name", value);
+        assertEquals(value, assignment.getValue());
+    }
+
+}

src/test/java/org/junit/tests/experimental/theories/TestedOnSupplierTest.java

@@ -21,7 +21,7 @@ public void foo(@TestedOn(ints = {1}) int x) {
     public void descriptionStatesParameterName() throws Exception {
         TestedOnSupplier supplier = new TestedOnSupplier();
         List<PotentialAssignment> assignments = supplier.getValueSources(signatureOfFoo());
-        assertThat(assignments.get(0).getDescription(), is("ints"));
+        assertThat(assignments.get(0).getDescription(), is("\"1\" <from ints>"));
     }
 
     private ParameterSignature signatureOfFoo() throws NoSuchMethodException {

src/test/java/org/junit/tests/experimental/theories/runner/UnsuccessfulWithDataPointFields.java

@@ -61,7 +61,7 @@ public void everythingIsZero(int x, int y) {
     @Test
     public void reportBadParams() throws Exception {
         assertThat(testResult(DoesntUseParams.class),
-                hasSingleFailureContaining("everythingIsZero(ONE, ONE)"));
+                hasSingleFailureContaining("everythingIsZero(\"1\" <from ONE>, \"1\" <from ONE>)"));
     }
 
     @RunWith(Theories.class)