Brian O'Connor | f3d0616 | 2014-10-02 15:54:12 -0700 | [diff] [blame] | 1 | package org.onlab.onos.net.intent; |
| 2 | //TODO is this the right package? |
| 3 | |
| 4 | import org.hamcrest.Description; |
| 5 | import org.hamcrest.StringDescription; |
| 6 | |
| 7 | import java.lang.reflect.Field; |
| 8 | import java.lang.reflect.Method; |
| 9 | import java.lang.reflect.Modifier; |
| 10 | |
| 11 | /** |
| 12 | * Hamcrest style class for verifying that a class follows the |
| 13 | * accepted rules for immutable classes. |
| 14 | * |
| 15 | * The rules that are enforced for immutable classes: |
| 16 | * - the class must be declared final |
| 17 | * - all data members of the class must be declared private and final |
| 18 | * - the class must not define any setter methods |
| 19 | */ |
| 20 | |
| 21 | public class ImmutableClassChecker { |
| 22 | |
| 23 | private String failureReason = ""; |
| 24 | |
| 25 | /** |
| 26 | * Method to determine if a given class is a properly specified |
| 27 | * immutable class. |
| 28 | * |
| 29 | * @param clazz the class to check |
| 30 | * @return true if the given class is a properly specified immutable class. |
| 31 | */ |
| 32 | private boolean isImmutableClass(Class<?> clazz) { |
| 33 | // class must be declared final |
| 34 | if (!Modifier.isFinal(clazz.getModifiers())) { |
| 35 | failureReason = "a class that is not final"; |
| 36 | return false; |
| 37 | } |
| 38 | |
| 39 | // class must have only final and private data members |
| 40 | for (final Field field : clazz.getDeclaredFields()) { |
| 41 | if (field.getName().startsWith("__cobertura")) { |
| 42 | // cobertura sticks these fields into classes - ignore them |
| 43 | continue; |
| 44 | } |
| 45 | if (!Modifier.isFinal(field.getModifiers())) { |
| 46 | failureReason = "a field named '" + field.getName() + |
| 47 | "' that is not final"; |
| 48 | return false; |
| 49 | } |
| 50 | if (!Modifier.isPrivate(field.getModifiers())) { |
| 51 | // |
| 52 | // NOTE: We relax the recommended rules for defining immutable |
| 53 | // objects and allow "static final" fields that are not |
| 54 | // private. The "final" check was already done above so we |
| 55 | // don't repeat it here. |
| 56 | // |
| 57 | if (!Modifier.isStatic(field.getModifiers())) { |
| 58 | failureReason = "a field named '" + field.getName() + |
| 59 | "' that is not private and is not static"; |
| 60 | return false; |
| 61 | } |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | // class must not define any setters |
| 66 | for (final Method method : clazz.getMethods()) { |
| 67 | if (method.getDeclaringClass().equals(clazz)) { |
| 68 | if (method.getName().startsWith("set")) { |
| 69 | failureReason = "a class with a setter named '" + method.getName() + "'"; |
| 70 | return false; |
| 71 | } |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | return true; |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Describe why an error was reported. Uses Hamcrest style Description |
| 80 | * interfaces. |
| 81 | * |
| 82 | * @param description the Description object to use for reporting the |
| 83 | * mismatch |
| 84 | */ |
| 85 | public void describeMismatch(Description description) { |
| 86 | description.appendText(failureReason); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * Describe the source object that caused an error, using a Hamcrest |
| 91 | * Matcher style interface. In this case, it always returns |
| 92 | * that we are looking for a properly defined utility class. |
| 93 | * |
| 94 | * @param description the Description object to use to report the "to" |
| 95 | * object |
| 96 | */ |
| 97 | public void describeTo(Description description) { |
| 98 | description.appendText("a properly defined immutable class"); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Assert that the given class adheres to the utility class rules. |
| 103 | * |
| 104 | * @param clazz the class to check |
| 105 | * |
| 106 | * @throws java.lang.AssertionError if the class is not a valid |
| 107 | * utility class |
| 108 | */ |
| 109 | public static void assertThatClassIsImmutable(Class<?> clazz) { |
| 110 | final ImmutableClassChecker checker = new ImmutableClassChecker(); |
| 111 | if (!checker.isImmutableClass(clazz)) { |
| 112 | final Description toDescription = new StringDescription(); |
| 113 | final Description mismatchDescription = new StringDescription(); |
| 114 | |
| 115 | checker.describeTo(toDescription); |
| 116 | checker.describeMismatch(mismatchDescription); |
| 117 | final String reason = |
| 118 | "\n" + |
| 119 | "Expected: is \"" + toDescription.toString() + "\"\n" + |
| 120 | " but : was \"" + mismatchDescription.toString() + "\""; |
| 121 | |
| 122 | throw new AssertionError(reason); |
| 123 | } |
| 124 | } |
| 125 | } |