ONOS checkin based on commit tag e796610b1f721d02f9b0e213cf6f7790c10ecd60

Change-Id: Ife8810491034fe7becdba75dda20de4267bd15cd

1 files changed, 149 insertions, 0 deletions

diff --git a/framework/src/onos/utils/junit/src/main/java/org/onlab/junit/UtilityClassChecker.java b/framework/src/onos/utils/junit/src/main/java/org/onlab/junit/UtilityClassChecker.java
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+++ b/framework/src/onos/utils/junit/src/main/java/org/onlab/junit/UtilityClassChecker.java
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+/*
+ * Copyright 2014 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.junit;
+
+import org.hamcrest.Description;
+import org.hamcrest.StringDescription;
+import org.onlab.junit.TestUtils.TestUtilsException;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+
+
+/**
+ * Hamcrest style class for verifying that a class follows the
+ * accepted rules for utility classes.
+ *
+ * The rules that are enforced for utility classes:
+ *    - the class must be declared final
+ *    - the class must have only one constructor
+ *    - the constructor must be private and inaccessible to callers
+ *    - the class must have only static methods
+ */
+
+public class UtilityClassChecker {
+
+    private String failureReason = "";
+
+    /**
+     * Method to determine if a given class is a properly specified
+     * utility class.  In addition to checking that the class meets the criteria
+     * for utility classes, an object of the class type is allocated to force
+     * test code coverage onto the class constructor.
+     *
+     * @param clazz the class to check
+     * @return true if the given class is a properly specified utility class.
+     */
+    private boolean isProperlyDefinedUtilityClass(Class<?> clazz) {
+        // class must be declared final
+        if (!Modifier.isFinal(clazz.getModifiers())) {
+            failureReason = "a class that is not final";
+            return false;
+        }
+
+        // class must have only one constructor
+        final Constructor<?>[] constructors = clazz.getDeclaredConstructors();
+        if (constructors.length != 1) {
+            failureReason = "a class with more than one constructor";
+            return false;
+        }
+
+        //  constructor must not be accessible outside of the class
+        final Constructor<?> constructor = constructors[0];
+        if (constructor.isAccessible()) {
+            failureReason = "a class with an accessible default constructor";
+            return false;
+        }
+
+        // constructor must be private
+        if (!Modifier.isPrivate(constructor.getModifiers())) {
+            failureReason = "a class with a default constructor that is not private";
+            return false;
+        }
+
+        // class must have only static methods
+        for (final Method method : clazz.getMethods()) {
+            if (method.getDeclaringClass().equals(clazz)) {
+                if (!Modifier.isStatic(method.getModifiers())) {
+                    failureReason = "a class with one or more non-static methods";
+                    return false;
+                }
+            }
+
+        }
+
+        try {
+            final Object newObject = TestUtils.callConstructor(constructor);
+            if (newObject == null) {
+                failureReason = "could not instantiate a new object";
+                return false;
+            }
+        } catch (TestUtilsException e) {
+            failureReason = "could not instantiate a new object";
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Describe why an error was reported.  Uses Hamcrest style Description
+     * interfaces.
+     *
+     * @param description the Description object to use for reporting the
+     *                    mismatch
+     */
+    public void describeMismatch(Description description) {
+        description.appendText(failureReason);
+    }
+
+    /**
+     * Describe the source object that caused an error, using a Hamcrest
+     * Matcher style interface.  In this case, it always returns
+     * that we are looking for a properly defined utility class.
+     *
+     * @param description the Description object to use to report the "to"
+     *                    object
+     */
+    public void describeTo(Description description) {
+        description.appendText("a properly defined utility class");
+    }
+
+    /**
+     * Assert that the given class adheres to the utility class rules.
+     *
+     * @param clazz the class to check
+     *
+     * @throws java.lang.AssertionError if the class is not a valid
+     *         utility class
+     */
+    public static void assertThatClassIsUtility(Class<?> clazz) {
+        final UtilityClassChecker checker = new UtilityClassChecker();
+        if (!checker.isProperlyDefinedUtilityClass(clazz)) {
+            final Description toDescription = new StringDescription();
+            final Description mismatchDescription = new StringDescription();
+
+            checker.describeTo(toDescription);
+            checker.describeMismatch(mismatchDescription);
+            final String reason =
+                "\n" +
+                "Expected: is \"" + toDescription.toString() + "\"\n" +
+                "    but : was \"" + mismatchDescription.toString() + "\"";
+
+            throw new AssertionError(reason);
+        }
+    }
+}