Lombok @NonNull Does Not Apply Check on Return Type

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IDE: Intellij

I am using Lombok's NonNull annotation to automatically generate Null Pointer Checks and throw exceptions on Method Arguments and Return Types.

On writing Unit Tests, the 'null' method Arguments do throw the exception, but the null return types do not throw exceptions.

import lombok.NonNull;
public @NonNull String function( @NonNull String input) {
    return null;
}

The following Test fails:

@Test
public void 
whenReturnTypeIsNull_ThenIllegalArgumentExceptionIsThrown(){
    assertThrows(IllegalArgumentException.class, ()-> testClass.function() );
}

With the Message:

Expected java.lang.IllegalArgumentException to be thrown, but nothing was thrown
junit5 lombok intellij-idea
1 Answers

The Lombok project documentation clearly states that the NonNull annotation allows to generate boilerplate null-checks for constructor and method arguments:

You can use @NonNull on the parameter of a method or constructor to have lombok generate a null-check statement for you.

Thus you should programatically check you return value invariants, including being non-null.

user_21065160
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