== true test

_[Original issue](https://code.google.com/p/error-prone/issues/detail?id=132) created by **grosse@google.com** on 2013-05-15 at 04:26 PM_

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Tests of the form (expr == true) are a potential security issue when interacting with untrusted bytecode, as the bytecode may return a boolean that is not equal to true or false. Booleans are compiled to 32bit ints, while the constants true and false are compiled to 1 and 0. Without an explicit equality test, all nonzero values are treated as true, so booleans will behave as Java programmers expect.

It might make sense to warn about both (== true) and (== false) even though the later doesn't present the same risk. People rarely write code like this, so it may indicate a programmer mistake.

Code containing these tests can be easily fixed. (var == true) is replaced with (var) while (var == false) is replaced with (!var).