Theories: only get all data points from enum and boolean types if the…

…re is no @FromDataPoints annotation, or the named data points represent a non-empty set of the same type.

Fixes junit-team#1648

src/main/java/org/junit/experimental/theories/internal/Assignments.java

@@ -6,7 +6,7 @@
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
-
+import org.junit.experimental.theories.FromDataPoints;
 import org.junit.experimental.theories.ParameterSignature;
 import org.junit.experimental.theories.ParameterSupplier;
 import org.junit.experimental.theories.ParametersSuppliedBy;
@@ -85,14 +85,16 @@ public List<PotentialAssignment> potentialsForNextUnassigned()
 
     private List<PotentialAssignment> generateAssignmentsFromTypeAlone(ParameterSignature unassigned) {
         Class<?> paramType = unassigned.getType();
-
-        if (paramType.isEnum()) {
-            return new EnumSupplier(paramType).getValueSources(unassigned);  
-        } else if (paramType.equals(Boolean.class) || paramType.equals(boolean.class)) {
-            return new BooleanSupplier().getValueSources(unassigned);
-        } else {
-            return emptyList();
+
+        FromDataPoints fromDataPoints = unassigned.getAnnotation(FromDataPoints.class);
+        if (fromDataPoints == null) {
+            if (paramType.isEnum()) {
+                return new EnumSupplier(paramType).getValueSources(unassigned);
+            } else if (paramType.equals(Boolean.class) || paramType.equals(boolean.class)) {
+                return new BooleanSupplier().getValueSources(unassigned);
+            }
         }
+        return emptyList();
     }
 
     private ParameterSupplier getSupplier(ParameterSignature unassigned)
@@ -150,4 +152,4 @@ public Object[] getArgumentStrings(boolean nullsOk)
         }
         return values;
     }
-}
+}

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

@@ -12,6 +12,7 @@
         TypeMatchingBetweenMultiDataPointsMethod.class,
         UnsuccessfulWithDataPointFields.class,
         WhenNoParametersMatch.class,
+        WhenNoParametersMatchEnumeratedTypes.class,
         WithAutoGeneratedDataPoints.class,
         WithDataPointMethod.class,
         WithExtendedParameterSources.class,

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

@@ -0,0 +1,83 @@
+package org.junit.tests.experimental.theories.runner;
+
+import static org.junit.Assert.assertThat;
+import static org.junit.experimental.results.PrintableResult.testResult;
+import static org.junit.experimental.results.ResultMatchers.failureCountIs;
+import static org.junit.experimental.results.ResultMatchers.hasFailureContaining;
+import static org.junit.experimental.results.ResultMatchers.hasSingleFailureContaining;
+
+import org.junit.Test;
+import org.junit.experimental.results.PrintableResult;
+import org.junit.experimental.theories.DataPoints;
+import org.junit.experimental.theories.FromDataPoints;
+import org.junit.experimental.theories.Theories;
+import org.junit.experimental.theories.Theory;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class WhenNoParametersMatchEnumeratedTypes {
+    public enum SomeEnum {
+      FIRST, SECOND
+    }
+
+    @RunWith(Theories.class)
+    public static class AssumptionsFailBoolean {
+        @Theory
+        public void shouldFailBecauseExplicitFromDataPointsNotKnown(
+                @FromDataPoints("unknown") boolean b) {}
+
+        @Theory
+        public void shouldSucceedBecauseNoExplicitFromDataPoints(boolean b) {}
+    }
+
+    @Test
+    public void showFailedAssumptionsWhenNoParametersFoundBoolean() {
+        assertThat(
+                testResult(AssumptionsFailBoolean.class),
+                hasSingleFailureContaining(
+                        "Never found parameters that satisfied method assumptions"));
+    }
+
+    @RunWith(Theories.class)
+    public static class AssumptionsFailEnum {
+        @Theory
+        public void shouldFailBecauseExplicitFromDataPointsNotKnown(
+                @FromDataPoints("unknown") SomeEnum e) {}
+
+        @Theory
+        public void shouldSucceedBecauseNoExplicitFromDataPoints(SomeEnum e) {}
+    }
+
+    @Test
+    public void showFailedAssumptionsWhenNoParametersFoundEnum() {
+        assertThat(
+                testResult(AssumptionsFailEnum.class),
+                hasSingleFailureContaining(
+                        "Never found parameters that satisfied method assumptions"));
+    }
+
+    @RunWith(Theories.class)
+    public static class AssumptionsFailWrongType {
+        @DataPoints("known") public static final String[] known = {"known"};
+
+        @Theory
+        public void shouldSucceedBecauseRightType(@FromDataPoints("known") String s) {}
+
+        @Theory
+        public void shouldFailBecauseWrongTypeBoolean(@FromDataPoints("known") boolean b) {}
+
+        @Theory
+        public void shouldFailBecauseWrongTypeEnum(@FromDataPoints("known") SomeEnum e) {}
+    }
+
+    @Test
+    public void showFailedAssumptionsWhenWrongType() {
+        PrintableResult result = testResult(AssumptionsFailWrongType.class);
+        assertThat(result, failureCountIs(2));
+        assertThat(
+                result,
+                hasFailureContaining(
+                        "Never found parameters that satisfied method assumptions"));
+    }
+}