t4018: an infrastructure to test hunk headers

Add an infrastructure that simplifies adding new tests of the hunk
header regular expressions.

To add new tests, a file with the syntax to test can be dropped in the
directory t4018. The README file explains how a test file must contain;
the README itself tests the default behavior.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/t/t4018/README b/t/t4018/README
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+How to write RIGHT test cases
+=============================
+
+Insert the word "ChangeMe" (exactly this form) at a distance of
+at least two lines from the line that must appear in the hunk header.
+
+The text that must appear in the hunk header must contain the word
+"right", but in all upper-case, like in the title above.
+
+To mark a test case that highlights a malfunction, insert the word
+BROKEN in all lower-case somewhere in the file.
+
+This text is a bit twisted and out of order, but it is itself a
+test case for the default hunk header pattern. Know what you are doing
+if you change it.
+
+BTW, this tests that the head line goes to the hunk header, not the line
+of equal signs.