lstree: Refactor parser test to generate data at runtime

The lstree's parser tests use static data of git-ls-tree(1) that has
been written into a set of files. This makes it hard to test this
package with SHA256 given that the output of course contains SHA1 object
hashes.

Refactor the tests to instead generate data at runtime. Note that we're
removing one of the two testcases in this process: both testcases do in
fact exercise the exact same logic, only that one of both has a space in
one of its tree entries. So we just retain the test for the tree entry
with the space and discard the other one given that they don't really
test different things anyway.

3 files changed, 37 insertions, 61 deletions

diff --git a/internal/git/lstree/parser_test.go b/internal/git/lstree/parser_test.go
index 6f8bb1912..3eb9a9111 100644
--- a/internal/git/lstree/parser_test.go
+++ b/internal/git/lstree/parser_test.go
@@ -3,91 +3,74 @@
 package lstree
 
 import (
+	"bytes"
 	"io"
-	"os"
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"gitlab.com/gitlab-org/gitaly/v15/internal/git"
+	"gitlab.com/gitlab-org/gitaly/v15/internal/git/gittest"
+	"gitlab.com/gitlab-org/gitaly/v15/internal/testhelper/testcfg"
 )
 
 func TestParser(t *testing.T) {
-	testCases := []struct {
-		desc     string
-		filename string
-		entries  Entries
+	t.Parallel()
+
+	cfg := testcfg.Build(t)
+	_, repoPath := gittest.InitRepo(t, cfg, cfg.Storages[0])
+
+	gitignoreBlobID := gittest.WriteBlob(t, cfg, repoPath, []byte("gitignore"))
+	gitmodulesBlobID := gittest.WriteBlob(t, cfg, repoPath, []byte("gitmodules"))
+	submoduleCommitID := gittest.WriteCommit(t, cfg, repoPath)
+
+	regularEntriesTreeID := gittest.WriteTree(t, cfg, repoPath, []gittest.TreeEntry{
+		{Path: ".gitignore", Mode: "100644", OID: gitignoreBlobID},
+		{Path: ".gitmodules", Mode: "100644", OID: gitmodulesBlobID},
+		{Path: "entry with space", Mode: "040000", OID: gittest.DefaultObjectHash.EmptyTreeOID},
+		{Path: "gitlab-shell", Mode: "160000", OID: submoduleCommitID},
+	})
+
+	for _, tc := range []struct {
+		desc            string
+		treeID          git.ObjectID
+		expectedEntries Entries
 	}{
 		{
-			desc:     "regular entries",
-			filename: "testdata/z-lstree.txt",
-			entries: Entries{
+			desc:   "regular entries",
+			treeID: regularEntriesTreeID,
+			expectedEntries: Entries{
 				{
 					Mode:     []byte("100644"),
 					Type:     Blob,
-					ObjectID: "dfaa3f97ca337e20154a98ac9d0be76ddd1fcc82",
+					ObjectID: gitignoreBlobID,
 					Path:     ".gitignore",
 				},
 				{
 					Mode:     []byte("100644"),
 					Type:     Blob,
-					ObjectID: "0792c58905eff3432b721f8c4a64363d8e28d9ae",
+					ObjectID: gitmodulesBlobID,
 					Path:     ".gitmodules",
 				},
 				{
 					Mode:     []byte("040000"),
 					Type:     Tree,
-					ObjectID: "3c122d2b7830eca25235131070602575cf8b41a1",
-					Path:     "encoding",
+					ObjectID: gittest.DefaultObjectHash.EmptyTreeOID,
+					Path:     "entry with space",
 				},
 				{
 					Mode:     []byte("160000"),
 					Type:     Submodule,
-					ObjectID: "79bceae69cb5750d6567b223597999bfa91cb3b9",
+					ObjectID: submoduleCommitID,
 					Path:     "gitlab-shell",
 				},
 			},
 		},
-		{
-			desc:     "irregular path",
-			filename: "testdata/z-lstree-irregular.txt",
-			entries: Entries{
-				{
-					Mode:     []byte("100644"),
-					Type:     Blob,
-					ObjectID: "dfaa3f97ca337e20154a98ac9d0be76ddd1fcc82",
-					Path:     ".gitignore",
-				},
-				{
-					Mode:     []byte("100644"),
-					Type:     Blob,
-					ObjectID: "0792c58905eff3432b721f8c4a64363d8e28d9ae",
-					Path:     ".gitmodules",
-				},
-				{
-					Mode:     []byte("040000"),
-					Type:     Tree,
-					ObjectID: "3c122d2b7830eca25235131070602575cf8b41a1",
-					Path:     "some encoding",
-				},
-				{
-					Mode:     []byte("160000"),
-					Type:     Submodule,
-					ObjectID: "79bceae69cb5750d6567b223597999bfa91cb3b9",
-					Path:     "gitlab-shell",
-				},
-			},
-		},
-	}
-
-	for _, testCase := range testCases {
-		t.Run(testCase.desc, func(t *testing.T) {
-			file, err := os.Open(testCase.filename)
-
-			require.NoError(t, err)
-			defer file.Close()
+	} {
+		t.Run(tc.desc, func(t *testing.T) {
+			treeData := gittest.Exec(t, cfg, "-C", repoPath, "ls-tree", "-z", tc.treeID.String())
 
+			parser := NewParser(bytes.NewReader(treeData))
 			parsedEntries := Entries{}
-
-			parser := NewParser(file)
 			for {
 				entry, err := parser.NextEntry()
 				if err == io.EOF {
@@ -98,14 +81,7 @@ func TestParser(t *testing.T) {
 				parsedEntries = append(parsedEntries, *entry)
 			}
 
-			expectedEntries := testCase.entries
-			require.Len(t, expectedEntries, len(parsedEntries))
-
-			for index, parsedEntry := range parsedEntries {
-				expectedEntry := expectedEntries[index]
-
-				require.Equal(t, expectedEntry, parsedEntry)
-			}
+			require.Equal(t, tc.expectedEntries, parsedEntries)
 		})
 	}
 }
diff --git a/internal/git/lstree/testdata/z-lstree-irregular.txt b/internal/git/lstree/testdata/z-lstree-irregular.txt
deleted file mode 100644
index ed55df3a4..000000000
--- a/internal/git/lstree/testdata/z-lstree-irregular.txt
+++ /dev/null
diff --git a/internal/git/lstree/testdata/z-lstree.txt b/internal/git/lstree/testdata/z-lstree.txt
deleted file mode 100644
index 653a2f8b1..000000000
--- a/internal/git/lstree/testdata/z-lstree.txt
+++ /dev/null