Question

I have a question about Tcl, we are using Tcl to write some test cases for c and c++ application. I saw some Tcl test cases are:

if {0} { #START:HELLO1
//some code here
}#END:HELLO1

if {0} { #START:HELLO2
//some code here
}#END:HELLO2

if {0} { #START:HELLO3
//some code here
}#END:HELLO3

How does these code works? #START: and #END: means what? and why they have index such as:

HELLO1 HELLO2 HELLO3

can anyone help me on this?

Answer 1

Those are very odd looking tests by Tcl terms. If they’d read like this (with the extra semicolon):

if {0} { #START:HELLO1
//some code here
};#END:HELLO1

Then they’d just be blocked out code that does nothing (literally; Tcl won’t attempt to generate code for it, just as a C or C++ compiler is unlikely to do much for if(0){...}) but the version you’ve got is just a syntax error. Braces shouldn’t be followed by anything other than whitespace (unless it is the special {*} syntax, which does expanding substitution).

That said, I’d expect testing code to look more like this:

doATest "the test name" {
    // Whatever makes the body of the test, in whatever language
}

The doATest might ignore the test based on some logic, but the overall script would be oblivious. (Tcl’s own built-in test harness — the tcltest package — follows this pattern with some extra parameters for controlling things like the conditions under which to run the test and the expected result.)