git/t/t4065-diff-anchored.sh
Jonathan Tan 2477ab2ea8 diff: support anchoring line(s)
Teach diff a new algorithm, one that attempts to prevent user-specified
lines from appearing as a deletion or addition in the end result. The
end user can use this by specifying "--anchored=<text>" one or more
times when using Git commands like "diff" and "show".

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-28 10:40:04 +09:00

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#!/bin/sh
test_description='anchored diff algorithm'
. ./test-lib.sh
test_expect_success '--anchored' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
# normally, c is moved to produce the smallest diff
test_expect_code 1 git diff --no-index pre post >diff &&
grep "^+c" diff &&
# with anchor, a is moved
test_expect_code 1 git diff --no-index --anchored=c pre post >diff &&
grep "^+a" diff
'
test_expect_success '--anchored multiple' '
printf "a\nb\nc\nd\ne\nf\n" >pre &&
printf "c\na\nb\nf\nd\ne\n" >post &&
# with 1 anchor, c is not moved, but f is moved
test_expect_code 1 git diff --no-index --anchored=c pre post >diff &&
grep "^+a" diff && # a is moved instead of c
grep "^+f" diff &&
# with 2 anchors, c and f are not moved
test_expect_code 1 git diff --no-index --anchored=c --anchored=f pre post >diff &&
grep "^+a" diff &&
grep "^+d" diff # d is moved instead of f
'
test_expect_success '--anchored with nonexistent line has no effect' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
test_expect_code 1 git diff --no-index --anchored=x pre post >diff &&
grep "^+c" diff
'
test_expect_success '--anchored with non-unique line has no effect' '
printf "a\nb\nc\nd\ne\nc\n" >pre &&
printf "c\na\nb\nc\nd\ne\n" >post &&
test_expect_code 1 git diff --no-index --anchored=c pre post >diff &&
grep "^+c" diff
'
test_expect_success 'diff still produced with impossible multiple --anchored' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
test_expect_code 1 git diff --no-index --anchored=a --anchored=c pre post >diff &&
mv post expected_post &&
# Ensure that the diff is correct by applying it and then
# comparing the result with the original
git apply diff &&
diff expected_post post
'
test_expect_success 'later algorithm arguments override earlier ones' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
test_expect_code 1 git diff --no-index --patience --anchored=c pre post >diff &&
grep "^+a" diff &&
test_expect_code 1 git diff --no-index --anchored=c --patience pre post >diff &&
grep "^+c" diff &&
test_expect_code 1 git diff --no-index --histogram --anchored=c pre post >diff &&
grep "^+a" diff &&
test_expect_code 1 git diff --no-index --anchored=c --histogram pre post >diff &&
grep "^+c" diff
'
test_expect_success '--anchored works with other commands like "git show"' '
printf "a\nb\nc\n" >file &&
git add file &&
git commit -m foo &&
printf "c\na\nb\n" >file &&
git add file &&
git commit -m foo &&
# with anchor, a is moved
git show --patience --anchored=c >diff &&
grep "^+a" diff
'
test_done