git/t/t4215-log-skewed-merges.sh
Derrick Stolee 0d251c3291 graph: drop assert() for merge with two collapsing parents
When "git log --graph" shows a merge commit that has two collapsing
lines, like:

    | | | | *
    | |_|_|/|
    |/| | |/
    | | |/|
    | |/| |
    | * | |
    * | | |

we trigger an assert():

        graph.c:1228: graph_output_collapsing_line: Assertion
                      `graph->mapping[i - 3] == target' failed.

The assert was introduced by eaf158f8 ("graph API: Use horizontal
lines for more compact graphs", 2009-04-21), which is quite old.
This assert is trying to say that when we complete a horizontal
line with a single slash, it is because we have reached our target.

It is actually the _second_ collapsing line that hits this assert.
The reason we are in this code path is because we are collapsing
the first line, and in that case we are hitting our target now
that the horizontal line is complete. However, the second line
cannot be a horizontal line, so it will collapse without horizontal
lines. In this case, it is inappropriate to assert that we have
reached our target, as we need to continue for another column
before reaching the target. Dropping the assert is safe here.

The new behavior in 0f0f389f12 (graph: tidy up display of
left-skewed merges, 2019-10-15) caused the behavior change that
made this assertion failure possible. In addition to making the
assert possible, it also changed how multiple edges collapse.

In a larger example, the current code will output a collapse
as follows:

	| | | | | | *
	| |_|_|_|_|/|\
	|/| | | | |/ /
	| | | | |/| /
	| | | |/| |/
	| | |/| |/|
	| |/| |/| |
	| | |/| | |
	| | * | | |

However, the intended collapse should allow multiple horizontal lines
as follows:

	| | | | | | *
	| |_|_|_|_|/|\
	|/| | | | |/ /
	| | |_|_|/| /
	| |/| | | |/
	| | | |_|/|
	| | |/| | |
	| | * | | |

This behavior is not corrected by this change, but is noted for a later
update.

Helped-by: Jeff King <peff@peff.net>
Reported-by: Bradley Smith <brad@brad-smith.co.uk>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-08 09:35:07 -08:00

286 lines
5.3 KiB
Bash
Executable file

#!/bin/sh
test_description='git log --graph of skewed merges'
. ./test-lib.sh
check_graph () {
cat >expect &&
git log --graph --pretty=tformat:%s "$@" >actual.raw &&
sed "s/ *$//" actual.raw >actual &&
test_cmp expect actual
}
test_expect_success 'log --graph with merge fusing with its left and right neighbors' '
git checkout --orphan _p &&
test_commit A &&
test_commit B &&
git checkout -b _q @^ && test_commit C &&
git checkout -b _r @^ && test_commit D &&
git checkout _p && git merge --no-ff _q _r -m E &&
git checkout _r && test_commit F &&
git checkout _p && git merge --no-ff _r -m G &&
git checkout @^^ && git merge --no-ff _p -m H &&
check_graph <<-\EOF
* H
|\
| * G
| |\
| | * F
| * | E
|/|\|
| | * D
| * | C
| |/
* / B
|/
* A
EOF
'
test_expect_success 'log --graph with left-skewed merge' '
git checkout --orphan 0_p && test_commit 0_A &&
git checkout -b 0_q 0_p && test_commit 0_B &&
git checkout -b 0_r 0_p &&
test_commit 0_C &&
test_commit 0_D &&
git checkout -b 0_s 0_p && test_commit 0_E &&
git checkout -b 0_t 0_p && git merge --no-ff 0_r^ 0_s -m 0_F &&
git checkout 0_p && git merge --no-ff 0_s -m 0_G &&
git checkout @^ && git merge --no-ff 0_q 0_r 0_t 0_p -m 0_H &&
check_graph <<-\EOF
*-----. 0_H
|\ \ \ \
| | | | * 0_G
| |_|_|/|
|/| | | |
| | | * | 0_F
| |_|/|\|
|/| | | |
| | | | * 0_E
| |_|_|/
|/| | |
| | * | 0_D
| | |/
| | * 0_C
| |/
|/|
| * 0_B
|/
* 0_A
EOF
'
test_expect_success 'log --graph with nested left-skewed merge' '
git checkout --orphan 1_p &&
test_commit 1_A &&
test_commit 1_B &&
test_commit 1_C &&
git checkout -b 1_q @^ && test_commit 1_D &&
git checkout 1_p && git merge --no-ff 1_q -m 1_E &&
git checkout -b 1_r @~3 && test_commit 1_F &&
git checkout 1_p && git merge --no-ff 1_r -m 1_G &&
git checkout @^^ && git merge --no-ff 1_p -m 1_H &&
check_graph <<-\EOF
* 1_H
|\
| * 1_G
| |\
| | * 1_F
| * | 1_E
|/| |
| * | 1_D
* | | 1_C
|/ /
* / 1_B
|/
* 1_A
EOF
'
test_expect_success 'log --graph with nested left-skewed merge following normal merge' '
git checkout --orphan 2_p &&
test_commit 2_A &&
test_commit 2_B &&
test_commit 2_C &&
git checkout -b 2_q @^^ &&
test_commit 2_D &&
test_commit 2_E &&
git checkout -b 2_r @^ && test_commit 2_F &&
git checkout 2_q &&
git merge --no-ff 2_r -m 2_G &&
git merge --no-ff 2_p^ -m 2_H &&
git checkout -b 2_s @^^ && git merge --no-ff 2_q -m 2_J &&
git checkout 2_p && git merge --no-ff 2_s -m 2_K &&
check_graph <<-\EOF
* 2_K
|\
| * 2_J
| |\
| | * 2_H
| | |\
| | * | 2_G
| |/| |
| | * | 2_F
| * | | 2_E
| |/ /
| * | 2_D
* | | 2_C
| |/
|/|
* | 2_B
|/
* 2_A
EOF
'
test_expect_success 'log --graph with nested right-skewed merge following left-skewed merge' '
git checkout --orphan 3_p &&
test_commit 3_A &&
git checkout -b 3_q &&
test_commit 3_B &&
test_commit 3_C &&
git checkout -b 3_r @^ &&
test_commit 3_D &&
git checkout 3_q && git merge --no-ff 3_r -m 3_E &&
git checkout 3_p && git merge --no-ff 3_q -m 3_F &&
git checkout 3_r && test_commit 3_G &&
git checkout 3_p && git merge --no-ff 3_r -m 3_H &&
git checkout @^^ && git merge --no-ff 3_p -m 3_J &&
check_graph <<-\EOF
* 3_J
|\
| * 3_H
| |\
| | * 3_G
| * | 3_F
|/| |
| * | 3_E
| |\|
| | * 3_D
| * | 3_C
| |/
| * 3_B
|/
* 3_A
EOF
'
test_expect_success 'log --graph with right-skewed merge following a left-skewed one' '
git checkout --orphan 4_p &&
test_commit 4_A &&
test_commit 4_B &&
test_commit 4_C &&
git checkout -b 4_q @^^ && test_commit 4_D &&
git checkout -b 4_r 4_p^ && git merge --no-ff 4_q -m 4_E &&
git checkout -b 4_s 4_p^^ &&
git merge --no-ff 4_r -m 4_F &&
git merge --no-ff 4_p -m 4_G &&
git checkout @^^ && git merge --no-ff 4_s -m 4_H &&
check_graph --date-order <<-\EOF
* 4_H
|\
| * 4_G
| |\
| * | 4_F
|/| |
| * | 4_E
| |\ \
| | * | 4_D
| |/ /
|/| |
| | * 4_C
| |/
| * 4_B
|/
* 4_A
EOF
'
test_expect_success 'log --graph with octopus merge with column joining its penultimate parent' '
git checkout --orphan 5_p &&
test_commit 5_A &&
git branch 5_q &&
git branch 5_r &&
test_commit 5_B &&
git checkout 5_q && test_commit 5_C &&
git checkout 5_r && test_commit 5_D &&
git checkout 5_p &&
git merge --no-ff 5_q 5_r -m 5_E &&
git checkout 5_q && test_commit 5_F &&
git checkout -b 5_s 5_p^ &&
git merge --no-ff 5_p 5_q -m 5_G &&
git checkout 5_r &&
git merge --no-ff 5_s -m 5_H &&
check_graph <<-\EOF
* 5_H
|\
| *-. 5_G
| |\ \
| | | * 5_F
| | * | 5_E
| |/|\ \
| |_|/ /
|/| | /
| | |/
* | | 5_D
| | * 5_C
| |/
|/|
| * 5_B
|/
* 5_A
EOF
'
test_expect_success 'log --graph with multiple tips' '
git checkout --orphan 6_1 &&
test_commit 6_A &&
git branch 6_2 &&
git branch 6_4 &&
test_commit 6_B &&
git branch 6_3 &&
test_commit 6_C &&
git checkout 6_2 && test_commit 6_D &&
git checkout 6_3 && test_commit 6_E &&
git checkout -b 6_5 6_1 &&
git merge --no-ff 6_2 -m 6_F &&
git checkout 6_4 && test_commit 6_G &&
git checkout 6_3 &&
git merge --no-ff 6_4 -m 6_H &&
git checkout 6_1 &&
git merge --no-ff 6_2 -m 6_I &&
check_graph 6_1 6_3 6_5 <<-\EOF
* 6_I
|\
| | * 6_H
| | |\
| | | * 6_G
| | * | 6_E
| | | | * 6_F
| |_|_|/|
|/| | |/
| | |/|
| |/| |
| * | | 6_D
| | |/
| |/|
* | | 6_C
| |/
|/|
* | 6_B
|/
* 6_A
EOF
'
test_done