parallel-checkout: add tests for basic operations

Add tests to populate the working tree during clone and checkout using
sequential and parallel mode, to confirm that they produce identical
results. Also test basic checkout mechanics, such as checking for
symlinks in the leading directories and the abidance to --force.

Note: some helper functions are added to a common lib file which is only
included by t2080 for now. But they will also be used by other
parallel-checkout tests in the following patches.

Co-authored-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 229 insertions, 0 deletions

diff --git a/t/t2080-parallel-checkout-basics.sh b/t/t2080-parallel-checkout-basics.sh
new file mode 100755
index 0000000..7087818
--- /dev/null
+++ b/t/t2080-parallel-checkout-basics.sh
@@ -0,0 +1,229 @@
+#!/bin/sh
+
+test_description='parallel-checkout basics
+
+Ensure that parallel-checkout basically works on clone and checkout, spawning
+the required number of workers and correctly populating both the index and the
+working tree.
+'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+. "$TEST_DIRECTORY/lib-parallel-checkout.sh"
+
+# Test parallel-checkout with a branch switch containing a variety of file
+# creations, deletions, and modifications, involving different entry types.
+# The branches B1 and B2 have the following paths:
+#
+#      B1                 B2
+#  a/a (file)         a   (file)
+#  b   (file)         b/b (file)
+#
+#  c/c (file)         c   (symlink)
+#  d   (symlink)      d/d (file)
+#
+#  e/e (file)         e   (submodule)
+#  f   (submodule)    f/f (file)
+#
+#  g   (submodule)    g   (symlink)
+#  h   (symlink)      h   (submodule)
+#
+# Additionally, the following paths are present on both branches, but with
+# different contents:
+#
+#  i   (file)         i   (file)
+#  j   (symlink)      j   (symlink)
+#  k   (submodule)    k   (submodule)
+#
+# And the following paths are only present in one of the branches:
+#
+#  l/l (file)         -
+#  -                  m/m (file)
+#
+test_expect_success 'setup repo for checkout with various types of changes' '
+	git init sub &&
+	(
+		cd sub &&
+		git checkout -b B2 &&
+		echo B2 >file &&
+		git add file &&
+		git commit -m file &&
+
+		git checkout -b B1 &&
+		echo B1 >file &&
+		git add file &&
+		git commit -m file
+	) &&
+
+	git init various &&
+	(
+		cd various &&
+
+		git checkout -b B1 &&
+		mkdir a c e &&
+		echo a/a >a/a &&
+		echo b >b &&
+		echo c/c >c/c &&
+		test_ln_s_add c d &&
+		echo e/e >e/e &&
+		git submodule add ../sub f &&
+		git submodule add ../sub g &&
+		test_ln_s_add c h &&
+
+		echo "B1 i" >i &&
+		test_ln_s_add c j &&
+		git submodule add -b B1 ../sub k &&
+		mkdir l &&
+		echo l/l >l/l &&
+
+		git add . &&
+		git commit -m B1 &&
+
+		git checkout -b B2 &&
+		git rm -rf :^.gitmodules :^k &&
+		mkdir b d f &&
+		echo a >a &&
+		echo b/b >b/b &&
+		test_ln_s_add b c &&
+		echo d/d >d/d &&
+		git submodule add ../sub e &&
+		echo f/f >f/f &&
+		test_ln_s_add b g &&
+		git submodule add ../sub h &&
+
+		echo "B2 i" >i &&
+		test_ln_s_add b j &&
+		git -C k checkout B2 &&
+		mkdir m &&
+		echo m/m >m/m &&
+
+		git add . &&
+		git commit -m B2 &&
+
+		git checkout --recurse-submodules B1
+	)
+'
+
+for mode in sequential parallel sequential-fallback
+do
+	case $mode in
+	sequential)          workers=1 threshold=0 expected_workers=0 ;;
+	parallel)            workers=2 threshold=0 expected_workers=2 ;;
+	sequential-fallback) workers=2 threshold=100 expected_workers=0 ;;
+	esac
+
+	test_expect_success "$mode checkout" '
+		repo=various_$mode &&
+		cp -R various $repo &&
+
+		# The just copied files have more recent timestamps than their
+		# associated index entries. So refresh the cached timestamps
+		# to avoid an "entry not up-to-date" error from `git checkout`.
+		# We only have to do this for the submodules as `git checkout`
+		# will already refresh the superproject index before performing
+		# the up-to-date check.
+		#
+		git -C $repo submodule foreach "git update-index --refresh" &&
+
+		set_checkout_config $workers $threshold &&
+		test_checkout_workers $expected_workers \
+			git -C $repo checkout --recurse-submodules B2 &&
+		verify_checkout $repo
+	'
+done
+
+for mode in parallel sequential-fallback
+do
+	case $mode in
+	parallel)            workers=2 threshold=0 expected_workers=2 ;;
+	sequential-fallback) workers=2 threshold=100 expected_workers=0 ;;
+	esac
+
+	test_expect_success "$mode checkout on clone" '
+		repo=various_${mode}_clone &&
+		set_checkout_config $workers $threshold &&
+		test_checkout_workers $expected_workers \
+			git clone --recurse-submodules --branch B2 various $repo &&
+		verify_checkout $repo
+	'
+done
+
+# Just to be paranoid, actually compare the working trees' contents directly.
+test_expect_success 'compare the working trees' '
+	rm -rf various_*/.git &&
+	rm -rf various_*/*/.git &&
+
+	# We use `git diff` instead of `diff -r` because the latter would
+	# follow symlinks, and not all `diff` implementations support the
+	# `--no-dereference` option.
+	#
+	git diff --no-index various_sequential various_parallel &&
+	git diff --no-index various_sequential various_parallel_clone &&
+	git diff --no-index various_sequential various_sequential-fallback &&
+	git diff --no-index various_sequential various_sequential-fallback_clone
+'
+
+# Currently, each submodule is checked out in a separated child process, but
+# these subprocesses must also be able to use parallel checkout workers to
+# write the submodules' entries.
+test_expect_success 'submodules can use parallel checkout' '
+	set_checkout_config 2 0 &&
+	git init super &&
+	(
+		cd super &&
+		git init sub &&
+		test_commit -C sub A &&
+		test_commit -C sub B &&
+		git submodule add ./sub &&
+		git commit -m sub &&
+		rm sub/* &&
+		test_checkout_workers 2 git checkout --recurse-submodules .
+	)
+'
+
+test_expect_success 'parallel checkout respects --[no]-force' '
+	set_checkout_config 2 0 &&
+	git init dirty &&
+	(
+		cd dirty &&
+		mkdir D &&
+		test_commit D/F &&
+		test_commit F &&
+
+		rm -rf D &&
+		echo changed >D &&
+		echo changed >F.t &&
+
+		# We expect 0 workers because there is nothing to be done
+		test_checkout_workers 0 git checkout HEAD &&
+		test_path_is_file D &&
+		grep changed D &&
+		grep changed F.t &&
+
+		test_checkout_workers 2 git checkout --force HEAD &&
+		test_path_is_dir D &&
+		grep D/F D/F.t &&
+		grep F F.t
+	)
+'
+
+test_expect_success SYMLINKS 'parallel checkout checks for symlinks in leading dirs' '
+	set_checkout_config 2 0 &&
+	git init symlinks &&
+	(
+		cd symlinks &&
+		mkdir D untracked &&
+		# Commit 2 files to have enough work for 2 parallel workers
+		test_commit D/A &&
+		test_commit D/B &&
+		rm -rf D &&
+		ln -s untracked D &&
+
+		test_checkout_workers 2 git checkout --force HEAD &&
+		! test -h D &&
+		grep D/A D/A.t &&
+		grep D/B D/B.t
+	)
+'
+
+test_done