How to ROLLBACK a transaction when testing using tSQLt

Question

I recently was calling a procedure that contained a rasierror in the code. The raiserror was in a try catch block. Also a BEGIN TRAN was in the same try catch block after

Answer 1

As I'm just reading up on tSQLt this was one of the first questions that came to mind when I've learned each test ran in a transactions. As some of my stored procedures do start transaction, some even use nested transactions, this can become challenging. What I've learned about nested transactions, if you apply the following rules you can keep your code clean of constant error checking and still handle errors gracefully.

• Always use a TRY/CATCH block when opening a transactions
• Always commit the transactions unless an error was raised
• Always rollback the transaction when an error is raised unless @@TRANCOUNT = 0
• Always reraise the error unless you're absolutely sure there was no transaction open at the start of the stored procedure.

Keeping those rules in mind here is an example of a proc implementation and test code to test it.

ALTER PROC testProc
    @IshouldFail BIT
AS
BEGIN TRY
    BEGIN TRAN

    IF @IshouldFail = 1
        RAISERROR('failure', 16, 1);

    COMMIT
END TRY
BEGIN CATCH
    IF @@TRANCOUNT > 0
        ROLLBACK;

    -- Do some exception handling

    -- You'll need to reraise the error to prevent exceptions about inconsistent 
    -- @@TRANCOUNT before / after execution of the stored proc.
    RAISERROR('failure', 16, 1);
END CATCH
GO


--EXEC tSQLt.NewTestClass 'tSQLt.experiments';
--GO
ALTER PROCEDURE [tSQLt.experiments].[test testProc nested transaction fails]
AS
BEGIN
    --Assemble
    DECLARE @CatchWasHit CHAR(1) = 'N';

    --Act
    BEGIN TRY
        EXEC dbo.testProc 1
    END TRY
    BEGIN CATCH 
        IF @@TRANCOUNT = 0
            BEGIN TRAN --reopen an transaction
        SET @CatchWasHit = 'Y';
    END CATCH

    --Assert
    EXEC tSQLt.AssertEqualsString @Expected = N'Y', @Actual = @CatchWasHit, @Message = N'Exception was expected'

END;
GO

ALTER PROCEDURE [tSQLt.experiments].[test testProc nested transaction succeeds]
AS
BEGIN
    --Act
    EXEC dbo.testProc 0

END;
GO

EXEC tSQLt.Run @TestName = N'tSQLt.experiments'