com.diffplug.common.testing

Class NullPointerTester

java.lang.Object

com.diffplug.common.testing.NullPointerTester

@Beta
public final class NullPointerTester
extends Object

A test utility that verifies that your methods and constructors throw NullPointerException or UnsupportedOperationException whenever null is passed to a parameter that isn’t annotated with Nullable.

The tested methods and constructors are invoked – each time with one parameter being null and the rest not null – and the test fails if no expected exception is thrown. NullPointerTester uses best effort to pick non-null default values for many common JDK and Guava types, and also for interfaces and public classes that have public parameter-less constructors. When the non-null default value for a particular parameter type cannot be provided by NullPointerTester, the caller can provide a custom non-null default value for the parameter type via setDefault(java.lang.Class<T>, T).

Since:

10.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NullPointerTester.Visibility Visibility of any method or constructor.

Constructor Summary

Constructors

Constructor and Description
NullPointerTester()

Method Summary

Modifier and Type	Method and Description
NullPointerTester	ignore(Method method) Ignore method in the tests that follow.
<T> NullPointerTester	setDefault(Class<T> type, T value) Sets a default value that can be used for any parameter of type type.
void	testAllPublicConstructors(Class<?> c) Runs testConstructor(java.lang.reflect.Constructor<?>) on every public constructor in class c.
void	testAllPublicInstanceMethods(Object instance) Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every public instance method of the class of instance, including those inherited from superclasses of the same package.
void	testAllPublicStaticMethods(Class<?> c) Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every public static method of class c, including those “inherited” from superclasses of the same package.
void	testConstructor(Constructor<?> ctor) Verifies that ctor produces a NullPointerException or UnsupportedOperationException whenever any of its non-Nullable parameters are null.
void	testConstructorParameter(Constructor<?> ctor, int paramIndex) Verifies that ctor produces a NullPointerException or UnsupportedOperationException when the parameter in position paramIndex is null.
void	testConstructors(Class<?> c, NullPointerTester.Visibility minimalVisibility) Runs testConstructor(java.lang.reflect.Constructor<?>) on every constructor in class c that has at least minimalVisibility.
void	testInstanceMethods(Object instance, NullPointerTester.Visibility minimalVisibility) Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every instance method of the class of instance with at least minimalVisibility, including those inherited from superclasses of the same package.
void	testMethod(Object instance, Method method) Verifies that method produces a NullPointerException or UnsupportedOperationException whenever any of its non-Nullable parameters are null.
void	testMethodParameter(Object instance, Method method, int paramIndex) Verifies that method produces a NullPointerException or UnsupportedOperationException when the parameter in position paramIndex is null.
void	testStaticMethods(Class<?> c, NullPointerTester.Visibility minimalVisibility) Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every static method of class c that has at least minimalVisibility, including those “inherited” from superclasses of the same package.

Methods inherited from class java.lang.Object

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

Constructor Detail

NullPointerTester

public NullPointerTester()

Method Detail

setDefault

public <T> NullPointerTester setDefault(Class<T> type,
                                        T value)

Sets a default value that can be used for any parameter of type type. Returns this object.

ignore

public NullPointerTester ignore(Method method)

Ignore method in the tests that follow. Returns this object.

Since:

13.0

testConstructors

public void testConstructors(Class<?> c,
                             NullPointerTester.Visibility minimalVisibility)

Runs testConstructor(java.lang.reflect.Constructor<?>) on every constructor in class c that has at least minimalVisibility.

testAllPublicConstructors

public void testAllPublicConstructors(Class<?> c)

Runs testConstructor(java.lang.reflect.Constructor<?>) on every public constructor in class c.

testStaticMethods

public void testStaticMethods(Class<?> c,
                              NullPointerTester.Visibility minimalVisibility)

Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every static method of class c that has at least minimalVisibility, including those “inherited” from superclasses of the same package.

testAllPublicStaticMethods

public void testAllPublicStaticMethods(Class<?> c)

Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every public static method of class c, including those “inherited” from superclasses of the same package.

testInstanceMethods

public void testInstanceMethods(Object instance,
                                NullPointerTester.Visibility minimalVisibility)

Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every instance method of the class of instance with at least minimalVisibility, including those inherited from superclasses of the same package.

testAllPublicInstanceMethods

public void testAllPublicInstanceMethods(Object instance)

Runs testMethod(java.lang.Object, java.lang.reflect.Method) on every public instance method of the class of instance, including those inherited from superclasses of the same package.

testMethod

public void testMethod(@Nullable
                       Object instance,
                       Method method)

Verifies that method produces a NullPointerException or UnsupportedOperationException whenever any of its non-Nullable parameters are null.

Parameters:

instance - the instance to invoke method on, or null if method is static

testConstructor

public void testConstructor(Constructor<?> ctor)

Verifies that ctor produces a NullPointerException or UnsupportedOperationException whenever any of its non-Nullable parameters are null.

testMethodParameter

public void testMethodParameter(@Nullable
                                Object instance,
                                Method method,
                                int paramIndex)

Verifies that method produces a NullPointerException or UnsupportedOperationException when the parameter in position paramIndex is null. If this parameter is marked Nullable, this method does nothing.

Parameters:

instance - the instance to invoke method on, or null if method is static

testConstructorParameter

public void testConstructorParameter(Constructor<?> ctor,
                                     int paramIndex)

Verifies that ctor produces a NullPointerException or UnsupportedOperationException when the parameter in position paramIndex is null. If this parameter is marked Nullable, this method does nothing.