shouldFail.kt

    /**
     * Use to wrap a block of code in a test that should throw an exception.
     * @param errorMsg Message to show if the block of code DOESN'T throw an exception. Optional.
     * @param withExceptionHaving Substring that the thrown exception must contain. Optional.
     * Checking exception strings is generally discouraged, and will cause the need to
     * periodically readjust the expected strings, but it guarantees the error is the expected one.
     */
    fun shouldFail(errorMsg: String = "Should have failed.", withExceptionHaving: String? = null, method: () -> Unit) {
        try {
            method()
            Assert.fail(errorMsg)
        } catch (e: Exception) {
            println("Test block failed with exception message: '${e.message}'.")
            withExceptionHaving?.let {
                Assert.assertTrue("Thrown exception message does not contain '$it'.", e.message!!.contains(it))
            }
        }
    }