t/t0000-basic.sh: Run the passing TODO test inside its own test-lib

Change the passing TODO test in t0000-basic.sh to run inside its own
test-lib.sh. The motivation is to have nothing out of the ordinary on
a normal test run for test smoking purposes.

If every normal test run has a passing TODO you're more likely to turn
a blind eye to it and not to investigate cases where things really are
passing unexpectedly.

It also makes the prove(1) output less noisy. Before:

    All tests successful.

    Test Summary Report
    -------------------
    ./t0000-basic.sh                                   (Wstat: 0 Tests: 46 Failed: 0)
      TODO passed:   5
    Files=484, Tests=6229, 143 wallclock secs ( 4.00 usr  4.15 sys + 104.77 cusr 351.57 csys = 464.49 CPU)
    Result: PASS

And after:

    All tests successful.
    Files=484, Tests=6228, 139 wallclock secs ( 4.07 usr  4.25 sys + 104.54 cusr 350.85 csys = 463.71 CPU)
    Result: PASS

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0000-basic.sh

@@ -54,9 +54,40 @@ test_expect_success 'success is reported like this' '
 test_expect_failure 'pretend we have a known breakage' '
     false
 '
+
+test_expect_success 'pretend we have fixed a known breakage (run in sub test-lib)' "
+    mkdir passing-todo &&
+    (cd passing-todo &&
+    cat >passing-todo.sh <<EOF &&
+#!$SHELL_PATH
+
+test_description='A passing TODO test
+
+This is run in a sub test-lib so that we do not get incorrect passing
+metrics
+'
+
+# Point to the t/test-lib.sh, which isn't in ../ as usual
+TEST_DIRECTORY=\"$TEST_DIRECTORY\"
+. \"\$TEST_DIRECTORY\"/test-lib.sh
+
 test_expect_failure 'pretend we have fixed a known breakage' '
     :
 '
+
+test_done
+EOF
+    chmod +x passing-todo.sh &&
+    ./passing-todo.sh >out 2>err &&
+    ! test -s err &&
+cat >expect <<EOF &&
+ok 1 - pretend we have fixed a known breakage # TODO known breakage
+# fixed 1 known breakage(s)
+# passed all 1 test(s)
+1..1
+EOF
+    test_cmp expect out)
+"
 test_set_prereq HAVEIT
 haveit=no
 test_expect_success HAVEIT 'test runs if prerequisite is satisfied' '