Improved PotentialAssignment description with better formatting, and handling for failed toString() calls. Refactored tests into proper unit tests closer wrapping the relevant bit of this code too.

Author: pimterry

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;
@@ -8,23 +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 String.format("%s: %s", name, value);
+            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: 1"));
+        assertThat(assignments.get(0).getDescription(), is("\"1\" <from ints>"));
     }
 
     private ParameterSignature signatureOfFoo() throws NoSuchMethodException {

src/test/java/org/junit/tests/experimental/theories/TheoryFailureMessagesTest.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: 1, ONE: 1)"));
+                hasSingleFailureContaining("everythingIsZero(\"1\" <from ONE>, \"1\" <from ONE>)"));
     }
 
     @RunWith(Theories.class)