Is there a way to test other assertions inside a test after calling tSQLt.ExpectException? - tsqlt

Question

Using tSQLt 1.0.5873.27393, I'm trying to write a tSQLt test for a stored procedure that records errors trapped in a CATCH block to a log table before re-throwing the error to the calling session.
I can successfully test that the error message is re-thrown using tSQLt.ExpectException, but a side effect seems to be that it's not possible to test any other assertions after calling tSQLt.ExpectException - so I am unable to test whether the error has been written to the log table.
The simplest test that I can come up with which demonstrates the problem is:
CREATE PROC MyTests.[test ExpectException]
AS
BEGIN
EXEC tSQLt.ExpectException;
THROW 50001, 'Error message',1
EXEC tSQLt.AssertEquals 0,1, '0=1'
END
GO
which produces the following (unexpected) output when executed:
|No|Test Case Name |Dur(ms)|Result |
+--+--------------------------------+-------+-------+
|1 |[MyTests].[test ExpectException]| 3|Success|
Using a profiler trace, I can see that the AssertEquals assertion is never executed, because the error is trapped by a CATCH block inside tSQLt.Private_RunTest.
Because tSQLt uses CATCH to trap errors, I suspect that there's no solution to this problem without a major rewrite of tSQLt - but I ask here just in case others have found a way around the issue.

Answer 1

You could follow this approach:
In the test, wrap your call to the tested stored procedure in a try/catch block.
Before the try/catch block, set up an expected variable to 1 and actual to 0.
In the test catch block, check if the log table got populated and if yes then flip the actual variable to 1.
Write your assertion AFTER the catch block.
CREATE PROC MyTests.[test ExpectException]
AS
BEGIN
DECLARE #expected bit = 1;
DECLARE #actual bit = 0;
BEGIN TRY
-- call tested SP, make sure it fails
CALL SP..;
-- add safety net, if the SP call doesn't fail then fail the test
RAISERROR('Fail the test', 16, 1);
END TRY
BEGIN CATCH
-- pseudo code
IF EXISTS (SELECT 1 FROM log table)
-> flip #actual to 1
END CATCH
EXEC tSQLt.AssertEquals #expected, #actual
END
GO

Answer 2

#Eduard Uta got there before I did, but I'll post this anyway.
It dawned on me almost as soon as I'd posted this that the obvious solution is to use a custom TRY...CATCH block, rather than the built-in tSQLt objects:
CREATE PROC MyTests.[test custom try catch]
AS
BEGIN
DECLARE #ErrorRaised bit = 0
BEGIN TRY
THROW 50001, 'Error message',1
END TRY
BEGIN CATCH
SET #ErrorRaised = 1
END CATCH
EXEC tSQLt.AssertEquals 1,#ErrorRaised, 'Error raised'
EXEC tSQLt.AssertEquals 0,1, '0=1'
END
GO
Here's an example which tests for a specific error message:
CREATE PROC MyTests.[test custom try catch test message]
AS
BEGIN
DECLARE #ErrorRaised bit = 0
BEGIN TRY
THROW 50001, 'Error message',1
END TRY
BEGIN CATCH
IF ERROR_MESSAGE() = 'Error message'
SET #ErrorRaised = 1
ELSE
THROW
END CATCH
EXEC tSQLt.AssertEquals 1,#ErrorRaised, 'Error raised'
EXEC tSQLt.AssertEquals 0,1, '0=1'
END
GO

Answer 3

For me, calling both the procedure under test and the tSQLt ExpectException proc inside a TRY...CATCH block seems to have done the trick.
CREATE PROC MyTests.[test ExpectException]
AS
BEGIN
BEGIN TRY
-- Call the proc that raises the error
EXEC offending_stored_proc
-- Tell tSQLt to expect the exception
EXEC tSQLt.ExpectException #ExpectedMessage = 'Expected error message', #ExpectedSeverity = NULL, #ExpectedState = NULL;
END TRY
BEGIN CATCH
-- No need to do anything here
END CATCH
END;
As expected, if the procedure raises the error with that error message, the test passes. If the error is not raised, the test fails.