Package com.google.errorprone.bugpatterns

Class AssertThrowsUtils

java.lang.Object

com.google.errorprone.bugpatterns.AssertThrowsUtils

public final class AssertThrowsUtils
extends Object

Utility methods for refactoring try-fail pattern to assertThrows, which is preferred. Used by TryFailRefactoring and MissingFail.

Method Summary

Modifier and Type	Method	Description
static Optional<Fix>	tryFailToAssertThrows(com.sun.source.tree.TryTree tryTree, List<? extends com.sun.source.tree.StatementTree> throwingStatements, Optional<com.sun.source.tree.Tree> failureMessage, VisitorState state)	Transforms a try-catch block in the try-fail pattern into a call to JUnit's assertThrows, inserting the behavior of the try block into a lambda parameter, and assigning the expected exception to a variable, if it is used within the catch block.

Methods inherited from class java.lang.Object

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

Method Details

tryFailToAssertThrows

public static Optional<Fix> tryFailToAssertThrows(com.sun.source.tree.TryTree tryTree,
 List<? extends com.sun.source.tree.StatementTree> throwingStatements,
 Optional<com.sun.source.tree.Tree> failureMessage,
 VisitorState state)

Transforms a try-catch block in the try-fail pattern into a call to JUnit's assertThrows, inserting the behavior of the try block into a lambda parameter, and assigning the expected exception to a variable, if it is used within the catch block. For example:

 try {
   foo();
   fail();
 } catch (MyException expected) {
   assertThat(expected).isEqualTo(other);
 }
 

becomes

 MyException expected = assertThrows(MyException.class, () -> foo());
 assertThat(expected).isEqualTo(other);
 

Parameters:

tryTree - the tree representing the try-catch block to be refactored.

throwingStatements - the list of statements in the throw clause, excluding the fail statement.

state - current visitor state (for source positions).

Returns:

an Optional containing a Fix that replaces tryTree with an equivalent assertThrows, if possible. Returns an Optional.empty() if a fix could not be constructed for the given code (e.g. multi-catch).