Prevent creation of FrameworkMethod or FrameworkField without underlying member.

The classes are relying on an underlying member. Fail early, because this makes it easier to find mistakes.

Author: stefanbirkner

src/main/java/org/junit/runners/model/FrameworkField.java

@@ -16,6 +16,10 @@ public class FrameworkField extends FrameworkMember<FrameworkField> {
     private final Field fField;
 
     FrameworkField(Field field) {
+        if (field == null) {
+            throw new NullPointerException(
+                    "FrameworkField cannot be created without an underlying field.");
+        }
         fField = field;
     }
 

src/main/java/org/junit/runners/model/FrameworkMethod.java

@@ -25,6 +25,10 @@ public class FrameworkMethod extends FrameworkMember<FrameworkMethod> {
      * Returns a new {@code FrameworkMethod} for {@code method}
      */
     public FrameworkMethod(Method method) {
+        if (method == null) {
+            throw new NullPointerException(
+                    "FrameworkMethod cannot be created without an underlying method.");
+        }
         fMethod = method;
     }
 

src/test/java/org/junit/runners/model/FrameworkFieldTest.java

@@ -0,0 +1,18 @@
+package org.junit.runners.model;
+
+import static org.junit.rules.ExpectedException.none;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class FrameworkFieldTest {
+    @Rule
+    public final ExpectedException thrown = none();
+
+    @Test
+    public void cannotBeCreatedWithoutUnderlyingField() {
+        thrown.expect(NullPointerException.class);
+        thrown.expectMessage("FrameworkField cannot be created without an underlying field.");
+        new FrameworkField(null);
+    }
+}

src/test/java/org/junit/runners/model/FrameworkMethodTest.java

@@ -0,0 +1,18 @@
+package org.junit.runners.model;
+
+import static org.junit.rules.ExpectedException.none;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class FrameworkMethodTest {
+    @Rule
+    public final ExpectedException thrown = none();
+
+    @Test
+    public void cannotBeCreatedWithoutUnderlyingField() {
+        thrown.expect(NullPointerException.class);
+        thrown.expectMessage("FrameworkMethod cannot be created without an underlying method.");
+        new FrameworkMethod(null);
+    }
+}

src/test/java/org/junit/tests/AllTests.java

@@ -15,6 +15,8 @@
 import org.junit.runner.notification.SynchronizedRunListenerTest;
 import org.junit.runners.Suite;
 import org.junit.runners.Suite.SuiteClasses;
+import org.junit.runners.model.FrameworkFieldTest;
+import org.junit.runners.model.FrameworkMethodTest;
 import org.junit.tests.assertion.AssertionTest;
 import org.junit.tests.assertion.ComparisonFailureTest;
 import org.junit.tests.assertion.MultipleFailureExceptionTest;
@@ -196,6 +198,8 @@
         JUnitCommandLineParseResultTest.class,
         FilterFactoriesTest.class,
         CategoryFilterFactoryTest.class,
+        FrameworkFieldTest.class,
+        FrameworkMethodTest.class,
         JUnitCoreTest.class
 })
 public class AllTests {