[PATCH 4/7] parallel-checkout: add tests for basic operations

[Matheus Tavares <matheus.bernardino@usp.br>]

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.

Original-patch-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---
 t/lib-parallel-checkout.sh          |  37 +++++++
 t/t2080-parallel-checkout-basics.sh | 150 ++++++++++++++++++++++++++++
 2 files changed, 187 insertions(+)
 create mode 100644 t/lib-parallel-checkout.sh
 create mode 100755 t/t2080-parallel-checkout-basics.sh

diff --git a/t/lib-parallel-checkout.sh b/t/lib-parallel-checkout.sh
new file mode 100644
index 0000000000..39fd36fdf6
--- /dev/null
+++ b/t/lib-parallel-checkout.sh
@@ -0,0 +1,37 @@
+# Helpers for t208* tests
+
+set_checkout_config () {
+	if test $# -ne 2
+	then
+		BUG "set_checkout_config() requires two arguments"
+	fi &&
+
+	test_config_global checkout.workers $1 &&
+	test_config_global checkout.thresholdForParallelism $2
+}
+
+# Run "${@:2}" and check that $1 checkout workers were used
+test_checkout_workers () {
+	if test $# -lt 2
+	then
+		BUG "too few arguments to test_checkout_workers()"
+	fi &&
+
+	expected_workers=$1 &&
+	shift &&
+
+	rm -f trace &&
+	GIT_TRACE2="$(pwd)/trace" "$@" &&
+
+	workers=$(grep "child_start\[..*\] git checkout--worker" trace | wc -l) &&
+	test $workers -eq $expected_workers &&
+	rm -f trace
+}
+
+# Verify that both the working tree and the index were created correctly
+verify_checkout () {
+	git -C "$1" diff-index --quiet HEAD -- &&
+	git -C "$1" diff-index --quiet --cached HEAD -- &&
+	git -C "$1" status --porcelain >"$1".status &&
+	test_must_be_empty "$1".status
+}
diff --git a/t/t2080-parallel-checkout-basics.sh b/t/t2080-parallel-checkout-basics.sh
new file mode 100755
index 0000000000..0cb1493cdc
--- /dev/null
+++ b/t/t2080-parallel-checkout-basics.sh
@@ -0,0 +1,150 @@
+#!/bin/sh
+
+test_description='parallel-checkout basics
+
+Ensure that parallel-checkout basically works on clone and checkout, spawning
+the required number of workers and correctly populating both the index and the
+working tree.
+'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+. "$TEST_DIRECTORY/lib-parallel-checkout.sh"
+
+# Test parallel-checkout with a branch switch containing file creations,
+# deletions, and modification; with different entry types. Switching from B1 to
+# B2 will have the following changes:
+#
+# - a (file):      modified
+# - e/x (file):    deleted
+# - b (symlink):   deleted
+# - b/f (file):    created
+# - e (symlink):   created
+# - d (submodule): created
+#
+test_expect_success SYMLINKS 'setup repo for checkout with various types of changes' '
+	git init various &&
+	(
+		cd various &&
+		git checkout -b B1 &&
+		echo a >a &&
+		mkdir e &&
+		echo e/x >e/x &&
+		ln -s e b &&
+		git add -A &&
+		git commit -m B1 &&
+
+		git checkout -b B2 &&
+		echo modified >a &&
+		rm -rf e &&
+		rm b &&
+		mkdir b &&
+		echo b/f >b/f &&
+		ln -s b e &&
+		git init d &&
+		test_commit -C d f &&
+		git submodule add ./d &&
+		git add -A &&
+		git commit -m B2 &&
+
+		git checkout --recurse-submodules B1
+	)
+'
+
+test_expect_success SYMLINKS 'sequential checkout' '
+	cp -R various various_sequential &&
+	set_checkout_config 1 0 &&
+	test_checkout_workers 0 \
+		git -C various_sequential checkout --recurse-submodules B2 &&
+	verify_checkout various_sequential
+'
+
+test_expect_success SYMLINKS 'parallel checkout' '
+	cp -R various various_parallel &&
+	set_checkout_config 2 0 &&
+	test_checkout_workers 2 \
+		git -C various_parallel checkout --recurse-submodules B2 &&
+	verify_checkout various_parallel
+'
+
+test_expect_success SYMLINKS 'fallback to sequential checkout (threshold)' '
+	cp -R various various_sequential_fallback &&
+	set_checkout_config 2 100 &&
+	test_checkout_workers 0 \
+		git -C various_sequential_fallback checkout --recurse-submodules B2 &&
+	verify_checkout various_sequential_fallback
+'
+
+test_expect_success SYMLINKS 'parallel checkout on clone' '
+	git -C various checkout --recurse-submodules B2 &&
+	set_checkout_config 2 0 &&
+	test_checkout_workers 2 \
+		git clone --recurse-submodules various various_parallel_clone &&
+	verify_checkout various_parallel_clone
+'
+
+test_expect_success SYMLINKS 'fallback to sequential checkout on clone (threshold)' '
+	git -C various checkout --recurse-submodules B2 &&
+	set_checkout_config 2 100 &&
+	test_checkout_workers 0 \
+		git clone --recurse-submodules various various_sequential_fallback_clone &&
+	verify_checkout various_sequential_fallback_clone
+'
+
+# Just to be paranoid, actually compare the working trees' contents directly.
+test_expect_success SYMLINKS 'compare the working trees' '
+	rm -rf various_*/.git &&
+	rm -rf various_*/d/.git &&
+
+	diff -r various_sequential various_parallel &&
+	diff -r various_sequential various_sequential_fallback &&
+	diff -r various_sequential various_parallel_clone &&
+	diff -r various_sequential various_sequential_fallback_clone
+'
+
+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
-- 
2.30.1