Re: [PATCH v4 6/6] list-objects-filter: implement filter tree:0

The "--filter" documentation should go with the other "--filter"
information, not right after --missing.

+test_expect_success 'setup for tests of tree:0' '
+	mkdir r1/subtree &&
+	echo "This is a file in a subtree" > r1/subtree/file &&
+	git -C r1 add subtree/file &&
+	git -C r1 commit -m subtree
+'

Style: no space after >

+test_expect_success 'grab tree directly when using tree:0' '
+	# We should get the tree specified directly but not its blobs or subtrees.
+	git -C r1 pack-objects --rev --stdout --filter=tree:0 >commitsonly.pack <<-EOF &&
+	HEAD:
+	EOF
+	git -C r1 index-pack ../commitsonly.pack &&
+	git -C r1 verify-pack -v ../commitsonly.pack >objs &&
+	grep -E "tree|blob" objs >trees_and_blobs &&
+	test_line_count = 1 trees_and_blobs
+'

Can we also verify that the SHA-1 in trees_and_blobs is what we
expected?

+test_expect_success 'use fsck before and after manually fetching a missing subtree' '
+	# push new commit so server has a subtree
+	mkdir src/dir &&
+	echo "in dir" > src/dir/file.txt &&

No space after >

+	git -C src add dir/file.txt &&
+	git -C src commit -m "file in dir" &&
+	git -C src push -u srv master &&
+	SUBTREE=$(git -C src rev-parse HEAD:dir) &&
+
+	rm -rf dst &&
+	git clone --no-checkout --filter=tree:0 "file://$(pwd)/srv.bare" dst &&
+	git -C dst fsck &&
+	git -C dst cat-file -p $SUBTREE >tree_contents 2>err &&
+	git -C dst fsck
+'

If you don't need to redirect to err, don't do so.

Before the cat-file, also verify that the tree is missing, most likely
through a "git rev-list" with "--missing=print".

And I would grep on the tree_contents to ensure that the filename
("file.txt") is there, so that we know that we got the correct tree.

+test_expect_success 'can use tree:0 to filter partial clone' '
+	rm -rf dst &&
+	git clone --no-checkout --filter=tree:0 "file://$(pwd)/srv.bare" dst &&
+	git -C dst rev-list master --missing=allow-any --objects >fetched_objects &&
+	cat fetched_objects \
+		| awk -f print_1.awk \
+		| xargs -n1 git -C dst cat-file -t >fetched_types &&
+	sort fetched_types -u >unique_types.observed &&
+	echo commit > unique_types.expected &&
+	test_cmp unique_types.observed unique_types.expected
+'
+
+test_expect_success 'auto-fetching of trees with --missing=error' '
+	git -C dst rev-list master --missing=error --objects >fetched_objects &&
+	cat fetched_objects \
+		| awk -f print_1.awk \
+		| xargs -n1 git -C dst cat-file -t >fetched_types &&
+	sort fetched_types -u >unique_types.observed &&
+	printf "blob\ncommit\ntree\n" >unique_types.expected &&
+	test_cmp unique_types.observed unique_types.expected
+'

These two tests seem redundant with the 'use fsck before and after
manually fetching a missing subtree' test (after the latter is
appropriately renamed). I think we only need to test this sequence once,
which can be placed in one or spread over multiple tests:

 1. partial clone with --filter=tree:0
 2. fsck works
 3. verify that trees are indeed missing
 4. autofetch a tree
 5. fsck still works