git/t/t6016-rev-list-graph-simplify-history.sh
James Coglan 92beecc136 graph: flatten edges that fuse with their right neighbor
When a merge commit is printed and its final parent is the same commit
that occupies the column to the right of the merge, this results in a
kink in the displayed edges:

        * |
        |\ \
        | |/
        | *

Graphs containing these shapes can be hard to read, as the expansion to
the right followed immediately by collapsing back to the left creates a
lot of zig-zagging edges, especially when many columns are present.

We can improve this by eliminating the zig-zag and having the merge's
final parent edge fuse immediately with its neighbor:

        * |
        |\|
        | *

This reduces the horizontal width for the current commit by 2, and
requires one less row, making the graph display more compact. Taken in
combination with other graph-smoothing enhancements, it greatly
compresses the space needed to display certain histories:

        *
        |\
        | *                       *
        | |\                      |\
        | | *                     | *
        | | |                     | |\
        | |  \                    | | *
        | *-. \                   | * |
        | |\ \ \        =>        |/|\|
        |/ / / /                  | | *
        | | | /                   | * |
        | | |/                    | |/
        | | *                     * /
        | * |                     |/
        | |/                      *
        * |
        |/
        *

One of the test cases here cannot be correctly rendered in Git v2.23.0;
it produces this output following commit E:

        | | *-. \   5_E
        | | |\ \ \
        | |/ / / /
        | | | / _
        | |_|/
        |/| |

The new implementation makes sure that the rightmost edge in this
history is not left dangling as above.

Signed-off-by: James Coglan <jcoglan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-16 11:11:25 +09:00

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#!/bin/sh
# There's more than one "correct" way to represent the history graphically.
# These tests depend on the current behavior of the graphing code. If the
# graphing code is ever changed to draw the output differently, these tests
# cases will need to be updated to know about the new layout.
test_description='--graph and simplified history'
. ./test-lib.sh
test_expect_success 'set up rev-list --graph test' '
# 3 commits on branch A
test_commit A1 foo.txt &&
test_commit A2 bar.txt &&
test_commit A3 bar.txt &&
git branch -m master A &&
# 2 commits on branch B, started from A1
git checkout -b B A1 &&
test_commit B1 foo.txt &&
test_commit B2 abc.txt &&
# 2 commits on branch C, started from A2
git checkout -b C A2 &&
test_commit C1 xyz.txt &&
test_commit C2 xyz.txt &&
# Octopus merge B and C into branch A
git checkout A &&
git merge B C &&
git tag A4 &&
test_commit A5 bar.txt &&
# More commits on C, then merge C into A
git checkout C &&
test_commit C3 foo.txt &&
test_commit C4 bar.txt &&
git checkout A &&
git merge -s ours C &&
git tag A6 &&
test_commit A7 bar.txt &&
# Store commit names in variables for later use
A1=$(git rev-parse --verify A1) &&
A2=$(git rev-parse --verify A2) &&
A3=$(git rev-parse --verify A3) &&
A4=$(git rev-parse --verify A4) &&
A5=$(git rev-parse --verify A5) &&
A6=$(git rev-parse --verify A6) &&
A7=$(git rev-parse --verify A7) &&
B1=$(git rev-parse --verify B1) &&
B2=$(git rev-parse --verify B2) &&
C1=$(git rev-parse --verify C1) &&
C2=$(git rev-parse --verify C2) &&
C3=$(git rev-parse --verify C3) &&
C4=$(git rev-parse --verify C4)
'
test_expect_success '--graph --all' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "| * $C3" >> expected &&
echo "* | $A5" >> expected &&
echo "| | " >> expected &&
echo "| \\ " >> expected &&
echo "*-. | $A4" >> expected &&
echo "|\\ \\| " >> expected &&
echo "| | * $C2" >> expected &&
echo "| | * $C1" >> expected &&
echo "| * | $B2" >> expected &&
echo "| * | $B1" >> expected &&
echo "* | | $A3" >> expected &&
echo "| |/ " >> expected &&
echo "|/| " >> expected &&
echo "* | $A2" >> expected &&
echo "|/ " >> expected &&
echo "* $A1" >> expected &&
git rev-list --graph --all > actual &&
test_cmp expected actual
'
# Make sure the graph_is_interesting() code still realizes
# that undecorated merges are interesting, even with --simplify-by-decoration
test_expect_success '--graph --simplify-by-decoration' '
rm -f expected &&
git tag -d A4 &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "| * $C3" >> expected &&
echo "* | $A5" >> expected &&
echo "| | " >> expected &&
echo "| \\ " >> expected &&
echo "*-. | $A4" >> expected &&
echo "|\\ \\| " >> expected &&
echo "| | * $C2" >> expected &&
echo "| | * $C1" >> expected &&
echo "| * | $B2" >> expected &&
echo "| * | $B1" >> expected &&
echo "* | | $A3" >> expected &&
echo "| |/ " >> expected &&
echo "|/| " >> expected &&
echo "* | $A2" >> expected &&
echo "|/ " >> expected &&
echo "* $A1" >> expected &&
git rev-list --graph --all --simplify-by-decoration > actual &&
test_cmp expected actual
'
test_expect_success 'setup: get rid of decorations on B' '
git tag -d B2 &&
git tag -d B1 &&
git branch -d B
'
# Graph with branch B simplified away
test_expect_success '--graph --simplify-by-decoration prune branch B' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "| * $C3" >> expected &&
echo "* | $A5" >> expected &&
echo "* | $A4" >> expected &&
echo "|\\| " >> expected &&
echo "| * $C2" >> expected &&
echo "| * $C1" >> expected &&
echo "* | $A3" >> expected &&
echo "|/ " >> expected &&
echo "* $A2" >> expected &&
echo "* $A1" >> expected &&
git rev-list --graph --simplify-by-decoration --all > actual &&
test_cmp expected actual
'
test_expect_success '--graph --full-history -- bar.txt' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "* | $A5" >> expected &&
echo "* | $A4" >> expected &&
echo "|\\| " >> expected &&
echo "* | $A3" >> expected &&
echo "|/ " >> expected &&
echo "* $A2" >> expected &&
git rev-list --graph --full-history --all -- bar.txt > actual &&
test_cmp expected actual
'
test_expect_success '--graph --full-history --simplify-merges -- bar.txt' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "* | $A5" >> expected &&
echo "* | $A3" >> expected &&
echo "|/ " >> expected &&
echo "* $A2" >> expected &&
git rev-list --graph --full-history --simplify-merges --all \
-- bar.txt > actual &&
test_cmp expected actual
'
test_expect_success '--graph -- bar.txt' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A5" >> expected &&
echo "* $A3" >> expected &&
echo "| * $C4" >> expected &&
echo "|/ " >> expected &&
echo "* $A2" >> expected &&
git rev-list --graph --all -- bar.txt > actual &&
test_cmp expected actual
'
test_expect_success '--graph --sparse -- bar.txt' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "* $A5" >> expected &&
echo "* $A4" >> expected &&
echo "* $A3" >> expected &&
echo "| * $C4" >> expected &&
echo "| * $C3" >> expected &&
echo "| * $C2" >> expected &&
echo "| * $C1" >> expected &&
echo "|/ " >> expected &&
echo "* $A2" >> expected &&
echo "* $A1" >> expected &&
git rev-list --graph --sparse --all -- bar.txt > actual &&
test_cmp expected actual
'
test_expect_success '--graph ^C4' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "* $A5" >> expected &&
echo "* $A4" >> expected &&
echo "|\\ " >> expected &&
echo "| * $B2" >> expected &&
echo "| * $B1" >> expected &&
echo "* $A3" >> expected &&
git rev-list --graph --all ^C4 > actual &&
test_cmp expected actual
'
test_expect_success '--graph ^C3' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "* $A5" >> expected &&
echo "* $A4" >> expected &&
echo "|\\ " >> expected &&
echo "| * $B2" >> expected &&
echo "| * $B1" >> expected &&
echo "* $A3" >> expected &&
git rev-list --graph --all ^C3 > actual &&
test_cmp expected actual
'
# I don't think the ordering of the boundary commits is really
# that important, but this test depends on it. If the ordering ever changes
# in the code, we'll need to update this test.
test_expect_success '--graph --boundary ^C3' '
rm -f expected &&
echo "* $A7" >> expected &&
echo "* $A6" >> expected &&
echo "|\\ " >> expected &&
echo "| * $C4" >> expected &&
echo "* | $A5" >> expected &&
echo "| | " >> expected &&
echo "| \\ " >> expected &&
echo "*-. \\ $A4" >> expected &&
echo "|\\ \\ \\ " >> expected &&
echo "| * | | $B2" >> expected &&
echo "| * | | $B1" >> expected &&
echo "* | | | $A3" >> expected &&
echo "o | | | $A2" >> expected &&
echo "|/ / / " >> expected &&
echo "o / / $A1" >> expected &&
echo " / / " >> expected &&
echo "| o $C3" >> expected &&
echo "|/ " >> expected &&
echo "o $C2" >> expected &&
git rev-list --graph --boundary --all ^C3 > actual &&
test_cmp expected actual
'
test_done