Jonathan Hart | 20d8e51 | 2014-10-16 11:05:52 -0700 | [diff] [blame] | 1 | package org.onlab.util; |
| 2 | |
| 3 | import java.lang.reflect.Constructor; |
| 4 | import java.lang.reflect.Field; |
| 5 | import java.lang.reflect.InvocationTargetException; |
| 6 | import java.lang.reflect.Method; |
| 7 | |
| 8 | |
| 9 | /** |
| 10 | * Utilities for testing. |
| 11 | */ |
| 12 | public final class TestUtils { |
| 13 | |
| 14 | /** |
| 15 | * Sets the field, bypassing scope restriction. |
| 16 | * |
| 17 | * @param subject Object where the field belongs |
| 18 | * @param fieldName name of the field to set |
| 19 | * @param value value to set to the field. |
| 20 | * @param <T> subject type |
| 21 | * @param <U> value type |
| 22 | * @throws TestUtilsException if there are reflection errors while setting |
| 23 | * the field |
| 24 | */ |
| 25 | public static <T, U> void setField(T subject, String fieldName, U value) |
| 26 | throws TestUtilsException { |
| 27 | @SuppressWarnings("unchecked") |
| 28 | Class<T> clazz = (Class<T>) subject.getClass(); |
| 29 | try { |
| 30 | Field field = clazz.getDeclaredField(fieldName); |
| 31 | field.setAccessible(true); |
| 32 | field.set(subject, value); |
| 33 | } catch (NoSuchFieldException | SecurityException | |
| 34 | IllegalArgumentException | IllegalAccessException e) { |
| 35 | throw new TestUtilsException("setField failed", e); |
| 36 | } |
| 37 | } |
| 38 | |
| 39 | /** |
| 40 | * Gets the field, bypassing scope restriction. |
| 41 | * |
| 42 | * @param subject Object where the field belongs |
| 43 | * @param fieldName name of the field to get |
| 44 | * @return value of the field. |
| 45 | * @param <T> subject type |
| 46 | * @param <U> field value type |
| 47 | * @throws TestUtilsException if there are reflection errors while getting |
| 48 | * the field |
| 49 | */ |
| 50 | public static <T, U> U getField(T subject, String fieldName) |
| 51 | throws TestUtilsException { |
| 52 | try { |
| 53 | @SuppressWarnings("unchecked") |
| 54 | Class<T> clazz = (Class<T>) subject.getClass(); |
| 55 | Field field = clazz.getDeclaredField(fieldName); |
| 56 | field.setAccessible(true); |
| 57 | |
| 58 | @SuppressWarnings("unchecked") |
| 59 | U result = (U) field.get(subject); |
| 60 | return result; |
| 61 | } catch (NoSuchFieldException | SecurityException | |
| 62 | IllegalArgumentException | IllegalAccessException e) { |
| 63 | throw new TestUtilsException("getField failed", e); |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Calls the method, bypassing scope restriction. |
| 69 | * |
| 70 | * @param subject Object where the method belongs |
| 71 | * @param methodName name of the method to call |
| 72 | * @param paramTypes formal parameter type array |
| 73 | * @param args arguments |
| 74 | * @return return value or null if void |
| 75 | * @param <T> subject type |
| 76 | * @param <U> return value type |
| 77 | * @throws TestUtilsException if there are reflection errors while calling |
| 78 | * the method |
| 79 | */ |
| 80 | public static <T, U> U callMethod(T subject, String methodName, |
| 81 | Class<?>[] paramTypes, Object...args) throws TestUtilsException { |
| 82 | |
| 83 | try { |
| 84 | @SuppressWarnings("unchecked") |
| 85 | Class<T> clazz = (Class<T>) subject.getClass(); |
| 86 | final Method method; |
| 87 | if (paramTypes == null || paramTypes.length == 0) { |
| 88 | method = clazz.getDeclaredMethod(methodName); |
| 89 | } else { |
| 90 | method = clazz.getDeclaredMethod(methodName, paramTypes); |
| 91 | } |
| 92 | method.setAccessible(true); |
| 93 | |
| 94 | @SuppressWarnings("unchecked") |
| 95 | U result = (U) method.invoke(subject, args); |
| 96 | return result; |
| 97 | } catch (NoSuchMethodException | SecurityException | |
| 98 | IllegalAccessException | IllegalArgumentException | |
| 99 | InvocationTargetException e) { |
| 100 | throw new TestUtilsException("callMethod failed", e); |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Calls the method, bypassing scope restriction. |
| 106 | * |
| 107 | * @param subject Object where the method belongs |
| 108 | * @param methodName name of the method to call |
| 109 | * @param paramType formal parameter type |
| 110 | * @param arg argument |
| 111 | * @return return value or null if void |
| 112 | * @param <T> subject type |
| 113 | * @param <U> return value type |
| 114 | * @throws TestUtilsException if there are reflection errors while calling |
| 115 | * the method |
| 116 | */ |
| 117 | public static <T, U> U callMethod(T subject, String methodName, |
| 118 | Class<?> paramType, Object arg) throws TestUtilsException { |
| 119 | return callMethod(subject, methodName, new Class<?>[]{paramType}, arg); |
| 120 | } |
| 121 | |
| 122 | /** |
| 123 | * Triggers an allocation of an object of type <T> and forces a call to |
| 124 | * the private constructor. |
| 125 | * |
| 126 | * @param constructor Constructor to call |
| 127 | * @param <T> type of the object to create |
| 128 | * @return created object of type <T> |
| 129 | * @throws TestUtilsException if there are reflection errors while calling |
| 130 | * the constructor |
| 131 | */ |
| 132 | public static <T> T callConstructor(Constructor<T> constructor) |
| 133 | throws TestUtilsException { |
| 134 | try { |
| 135 | constructor.setAccessible(true); |
| 136 | return constructor.newInstance(); |
| 137 | } catch (InstantiationException | IllegalAccessException | |
| 138 | InvocationTargetException error) { |
| 139 | throw new TestUtilsException("callConstructor failed", error); |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * Avoid instantiation. |
| 145 | */ |
| 146 | private TestUtils() {} |
| 147 | |
| 148 | /** |
| 149 | * Exception that can be thrown if problems are encountered while executing |
| 150 | * the utility method. These are usually problems accessing fields/methods |
| 151 | * through reflection. The original exception can be found by examining the |
| 152 | * cause. |
| 153 | */ |
| 154 | public static class TestUtilsException extends Exception { |
| 155 | |
| 156 | private static final long serialVersionUID = 1L; |
| 157 | |
| 158 | /** |
| 159 | * Constructs a new exception with the specified detail message and |
| 160 | * cause. |
| 161 | * |
| 162 | * @param message the detail message |
| 163 | * @param cause the original cause of this exception |
| 164 | */ |
| 165 | public TestUtilsException(String message, Throwable cause) { |
| 166 | super(message, cause); |
| 167 | } |
| 168 | } |
| 169 | } |