A failing test

A test earns its keep the day it fails. Here WordCount counts the spaces instead of the words, and the test catches it:

#include once "fbcunit.bi"

'' Meant to count the words in s -- but it counts the spaces.
function WordCount( byval s as ustring ) as int32
    dim as int32 n = 0
    for i as int32 = 1 to len( s )
        if mid( s, i, 1 ) = " " then n += 1
    next
    return n
end function

SUITE( words )
    TEST( counts_words )
        CU_ASSERT_EQUAL( WordCount( "" ), 0 )
        CU_ASSERT_EQUAL( WordCount( "one two three" ), 3 )
        CU_ASSERT_EQUAL( WordCount( "single" ), 1 )
    END_TEST
END_SUITE

end iif( fbcu.run_tests( ), 0, 1 )

Output

      failing.tiko(15) : error : TESTS.WORDS.COUNTS_WORDS CU_ASSERT_EQUAL(WordCount( "one two three" ),3)
      failing.tiko(16) : error : TESTS.WORDS.COUNTS_WORDS CU_ASSERT_EQUAL(WordCount( "single" ),1)

SUMMARY

 Asserts    Passed    Failed  Suite                                      Tests
--------  --------  --------  --------------------------------------  --------
       3         1         2  words                                          1
--------  --------  --------  --------------------------------------  --------
       3         1         2  Total                                          1

The program exits with code 1.

Each failed assertion is printed before the summary with three things you need to find it: the file and line, the test's full name (TESTS.WORDS.COUNTS_WORDS, the suite and test in capitals), and the assertion as it was written. The first check passed, because the empty string has no spaces either; the other two failed.

The summary's Failed column is the number of failed assertions, not of failed tests, and run_tests returns false when it is anything but zero. That is why the exit code is 1: a build script that runs the tests stops here.

Write the test that shows a bug before you fix the bug. When the test passes, you know the fix works, and the test stays to make sure the bug does not come back.

Activities

1. Fix WordCount (count the starts of words, not the spaces) and run the tests again.
2. Add CU_ASSERT_EQUAL( WordCount( "two spaces" ), 2 ) and check that your fix handles it.