com.gmail.bertcarnell.assertextensions

Class ExceptionAssertExtensions

java.lang.Object

com.gmail.bertcarnell.assertextensions.ExceptionAssertExtensions

public class ExceptionAssertExtensions
extends Object

Adds additional Assert methods to the JUnit implementation

The AssertThrow methods are necessary for a couple of reasons

• The @Test(exception=..) paradigm does not work because it is only looking for at least one statement in a test method to throw. If there are multiple statements in the test method that should throw, then they would have to be broken out into individual test methods
• The try{statement; fail()}catch(Exception){assertTrue(true)} paradigm works, but is unacceptably long and redundant in the test code.
• The Exception class also has the same drawbacks as the @Test paradigm.

Author:

Robert Carnell (bertcarnell@gmail.com), Dave Rigsby, Mariano Navas

Method Summary

Methods

Modifier and Type	Method and Description
static void	assertConstuctorThrows(Class<? extends Throwable> expectedException, Constructor<?> constr, Object... arguments) assertThrows for Constructors using reflection
static void	assertThrows(Class<? extends Throwable> expectedException, Object target, String methodName, Object... arguments) Unit test to assert that a specific type of exception is thrown
static <T extends Throwable> void	assertThrows(Class<T> excType, Runnable throwerClosure) Checks that the logic wrapped by the given Runnable throw an exception of the specified type (only valid for RuntimeExceptions given that the run method of the Runnable interface exposes no throws signature).
static <T extends Throwable> void	assertThrows(Class<T> excType, Runnable throwerClosure, String customFailMessage) Similar to the other assertThrows methods.
static void	assertThrows(String message, Class<? extends Throwable> expectedException, Object target, String methodName, Object... arguments) Unit test to assert that a specific type of exception with a specific message is thrown
static <T extends Throwable> void	assertThrows(String excMessage, Class<T> excType, Runnable throwerClosure) Assert that a method in a Runnable closure should throw when tested
static <T extends Throwable> void	assertThrows(String excMessage, Class<T> excType, Runnable throwerClosure, String customFailMessage) Assert that a method in a Runnable closure should throw when tested
static <T extends Throwable> void	assertThrowsAndDoAssertsInCatch(Class<T> excType, ExceptionAssertionsPerformer<T> excAssertsPerformer) Checks if the given exception type is thrown and perform the given assertions in that exception object.
static <T extends Throwable> void	assertThrowsAndDoAssertsInCatch(Class<T> excType, ExceptionAssertionsPerformer<T> excAssertsPerformer, String customFailMessage) Similar to the method with the same name.
static <T extends Throwable> void	assertThrowsSpecificException(String excMessage, Class<T> excType, ExceptionAssertionsPerformer<T> excAssertsPerformer, String customFailMessage) Assert that a method in a Runnable closure should throw when tested with a specific message

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

assertThrows

public static <T extends Throwable> void assertThrows(@NotNull
                                      Class<T> excType,
                                      @NotNull
                                      Runnable throwerClosure)

Checks that the logic wrapped by the given Runnable throw an exception of the specified type (only valid for RuntimeExceptions given that the run method of the Runnable interface exposes no throws signature).

Parameters:

excType - The Class corresponding to the expected exception.

throwerClosure - Closure-like object that represents the code expected to throw an exception.

assertThrows

public static <T extends Throwable> void assertThrows(Class<T> excType,
                                      Runnable throwerClosure,
                                      String customFailMessage)

Similar to the other assertThrows methods. Allows the user to pass a custom fail message in case the assertion doesn't pass.

Parameters:

excType - The Class corresponding to the expected exception.

throwerClosure - Closure-like object that represents the code expected to throw an exception.

customFailMessage - Message to throw if the wrong exception is thrown

assertThrowsAndDoAssertsInCatch

public static <T extends Throwable> void assertThrowsAndDoAssertsInCatch(Class<T> excType,
                                                         ExceptionAssertionsPerformer<T> excAssertsPerformer)

Checks if the given exception type is thrown and perform the given assertions in that exception object.

Parameters:

excType - The Class corresponding to the expected exception.

excAssertsPerformer - An object that provides methods to perform that will throw and methods to perform after the catch.

assertThrowsAndDoAssertsInCatch

public static <T extends Throwable> void assertThrowsAndDoAssertsInCatch(Class<T> excType,
                                                         ExceptionAssertionsPerformer<T> excAssertsPerformer,
                                                         String customFailMessage)

Similar to the method with the same name. Allows us to customize the error message.

Parameters:

excType - The Class corresponding to the expected exception.

excAssertsPerformer - An object that provides methods to perform that will throw and methods to perform after the catch.

customFailMessage - Message to throw if the wrong exception is thrown

assertThrows

public static <T extends Throwable> void assertThrows(@NotNull
                                      String excMessage,
                                      @NotNull
                                      Class<T> excType,
                                      @NotNull
                                      Runnable throwerClosure)

Assert that a method in a Runnable closure should throw when tested

Type Parameters:

T - A class that extends Throwable

Parameters:

excMessage - the expected message from the exception

excType - The Class corresponding to the expected exception.

throwerClosure - Closure-like object that represents the code expected to throw an exception.

assertThrows

public static <T extends Throwable> void assertThrows(@NotNull
                                      String excMessage,
                                      @NotNull
                                      Class<T> excType,
                                      @NotNull
                                      Runnable throwerClosure,
                                      String customFailMessage)

Assert that a method in a Runnable closure should throw when tested

Type Parameters:

T - A class that extends Throwable

Parameters:

excMessage - the expected message from the exception

excType - The Class corresponding to the expected exception.

throwerClosure - Closure-like object that represents the code expected to throw an exception.

customFailMessage - A message to be displayed on failure

assertThrowsSpecificException

public static <T extends Throwable> void assertThrowsSpecificException(String excMessage,
                                                       @NotNull
                                                       Class<T> excType,
                                                       @NotNull
                                                       ExceptionAssertionsPerformer<T> excAssertsPerformer,
                                                       String customFailMessage)

Assert that a method in a Runnable closure should throw when tested with a specific message

Type Parameters:

T - A class that extends Throwable

Parameters:

excMessage - the expected message from the exception

excType - The Class corresponding to the expected exception.

excAssertsPerformer - An object that provides methods to perform that will throw and methods to perform after the catch.

customFailMessage - A message to be displayed on failure

assertThrows

public static void assertThrows(@NotNull
                Class<? extends Throwable> expectedException,
                @NotNull
                Object target,
                @NotNull
                String methodName,
                Object... arguments)

Unit test to assert that a specific type of exception is thrown

Examples:

• Assert passes because the right exception is thrown:
  • assertThrows(NumberFormatException.class, new Double(0), "parseDouble", "a");
• Assert fails because the wrong exception is thrown:
  • assertThrows(ArithmeticException.class, new Double(0), "parseDouble", "a");
• Assert fails because an exception isn't thrown by the method when one is expected
  • assertThrows(NumberFormatException.class, new Double(0), "parseDouble", "1");

Parameters:

expectedException - The class of the expected exception type

target - the target object that the method will be called from

methodName - the name of the method that is to be called

arguments - the arguments to be passed to the method

assertThrows

public static void assertThrows(@NotNull
                String message,
                @NotNull
                Class<? extends Throwable> expectedException,
                @NotNull
                Object target,
                @NotNull
                String methodName,
                Object... arguments)

Unit test to assert that a specific type of exception with a specific message is thrown

Parameters:

message - The expected message

expectedException - The class of the expected exception type

target - the target object that the method will be called from

methodName - the name of the method that is to be called

arguments - the arguments to be passed to the method

assertConstuctorThrows

public static void assertConstuctorThrows(@NotNull
                          Class<? extends Throwable> expectedException,
                          @NotNull
                          Constructor<?> constr,
                          Object... arguments)

assertThrows for Constructors using reflection

Warning: This method cannot tell the difference between constructors when the only difference is a primitive type. For example, it cannot tell the difference between A(double[], Object, double) and A(double[], Object, int)

Parameters:

expectedException - The class of the expected exception type

constr - the target constructor

arguments - the arguments to be passed to the constructor