net.obvj.junit.utils.matchers

Class InstantiationNotAllowedMatcher

java.lang.Object

org.hamcrest.BaseMatcher<T>

org.hamcrest.TypeSafeDiagnosingMatcher<Class<?>>

net.obvj.junit.utils.matchers.InstantiationNotAllowedMatcher

All Implemented Interfaces:

org.hamcrest.Matcher<Class<?>>, org.hamcrest.SelfDescribing

public class InstantiationNotAllowedMatcher
extends org.hamcrest.TypeSafeDiagnosingMatcher<Class<?>>

A Matcher that checks that instantiation is not allowed for a given class, which is particularly useful for utility classes, for example.

First, the matcher verifies that all declared constructors are private, then it tries to produce a new instance using the default constructor, via Reflection.

A matching class should have all constructors declared as private and throw an exception, so the class will never be instantiated.

For example:

 private MyClass()
 {
     throw new UnsupportedOperationException("Instantiation not allowed");
 }
 

Since:

1.1.0

Author:

oswaldo.bapvic.jr

Constructor Summary

Constructors

Constructor and Description
InstantiationNotAllowedMatcher()

Method Summary

Modifier and Type	Method and Description
void	describeTo(org.hamcrest.Description description) Describes the "expected" pat of the test description.
static InstantiationNotAllowedMatcher	instantiationNotAllowed() Creates a matcher that matches if the examined class cannot be instantiated, which is particularly useful for utility classes.
InstantiationNotAllowedMatcher	throwing(Class<? extends Exception> exception) Assigns an expected Exception (optional step).
InstantiationNotAllowedMatcher	withMessage(org.hamcrest.Matcher<String> matcher) Assigns an external Matcher to be used in combination for the exception message validation (optional).
InstantiationNotAllowedMatcher	withMessage(String message) Assigns an expected message for Exception validation (optional).

Methods inherited from class org.hamcrest.TypeSafeDiagnosingMatcher

describeMismatch, matches

Methods inherited from class org.hamcrest.BaseMatcher

_dont_implement_Matcher___instead_extend_BaseMatcher_, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

InstantiationNotAllowedMatcher

public InstantiationNotAllowedMatcher()

Method Detail

instantiationNotAllowed

public static InstantiationNotAllowedMatcher instantiationNotAllowed()

Creates a matcher that matches if the examined class cannot be instantiated, which is particularly useful for utility classes.

For example:

 assertThat(TestUtils.class, instantiationNotAllowed());
 

Returns:

the matcher

throwing

public InstantiationNotAllowedMatcher throwing(Class<? extends Exception> exception)

Assigns an expected Exception (optional step).

For example:

 
 assertThat(TestUtils.class, instantiationNotAllowed()
         .throwing(IllegalStateException.class));
 

The matcher matches if the actual exception class is either the same as, or is a child of, the Exception represented by the specified parameter.

For example, if the constructor throws a NullPointerException, all of the following assertions are valid:

 throwing(IllegalStateException.class);
 throwing(RuntimeException.class);
 throwing(Exception.class);
 

In other words, the matcher tests whether the actual exception can be converted to the specified class.

Parameters:

exception - the expected exception class; must not be null

Returns:

the matcher, incremented with an expected exception

Throws:

NullPointerException - if the specified class is null

Since:

1.2.1

withMessage

public InstantiationNotAllowedMatcher withMessage(String message)

Assigns an expected message for Exception validation (optional).

For example:

 
 assertThat(TestUtils.class, instantiationNotAllowed()
         .throwing(IllegalStateException.class)
             .withMessage("instantiation not allowed"));
 

The following example is also valid for a test where any Exception is acceptable, provided that the message matches:

 
 assertThat(TestUtils.class, instantiationNotAllowed()
         .withMessage("instantiation not allowed"));
 

Parameters:

message - the message for exception validation

Returns:

the matcher, incremented with the specified message for testing

Since:

1.2.1

withMessage

public InstantiationNotAllowedMatcher withMessage(org.hamcrest.Matcher<String> matcher)

Assigns an external Matcher to be used in combination for the exception message validation (optional).

For example:

 
 assertThat(TestUtils.class, instantiationNotAllowed()
         .throwing(IllegalStateException.class)
             .withMessage(containsString("not allowed")));
 

The following example is also valid for a test where any Exception is acceptable, provided that the message matches:

 
 assertThat(TestUtils.class, instantiationNotAllowed()
         .withMessage(endsWith("not allowed")));
 

Parameters:

matcher - the matcher to be used in combination for exception message validation

Returns:

the matcher, incremented with the specified matcher for exception testing

Since:

1.2.1

describeTo

public void describeTo(org.hamcrest.Description description)

Describes the "expected" pat of the test description.

Parameters:

description - the Description to be appended to