gittest: Introduce default object hash

The gittest package is currently re-exporting the functionality provided
by the `ObjectHash` structure. Depending on whether we are testing with
SHA1 or SHA256, we export either the implementation details of the
`ObjectHashSHA1` or `ObjectHashSHA256` structure.

Now that we have the hash-specific information neatly encapsulated in
its own structure there is no need to re-export the separate details of
that structure anymore. Instead, refactor the gittest package to only
export a single `DefaultObjectHash` variable that points to one of the
above structures, depending on what we're currently testing.

7 files changed, 17 insertions, 30 deletions

diff --git a/internal/git/gittest/commit.go b/internal/git/gittest/commit.go
index 7b4b14440..f8902ffe4 100644
--- a/internal/git/gittest/commit.go
+++ b/internal/git/gittest/commit.go
@@ -150,7 +150,7 @@ func WriteCommit(t testing.TB, cfg config.Cfg, repoPath string, opts ...WriteCom
 		tree = writeCommitConfig.treeID.String()
 	} else if len(parents) == 0 {
 		// If there are no parents, then we set the root tree to the empty tree.
-		tree = EmptyTreeOID.String()
+		tree = DefaultObjectHash.EmptyTreeOID.String()
 	} else {
 		tree = parents[0].String() + "^{tree}"
 	}
@@ -210,7 +210,7 @@ func WriteCommit(t testing.TB, cfg config.Cfg, repoPath string, opts ...WriteCom
 		Stdin: stdin,
 		Env:   env,
 	}, commitArgs...)
-	oid, err := NewObjectIDFromHex(text.ChompBytes(stdout))
+	oid, err := DefaultObjectHash.FromHex(text.ChompBytes(stdout))
 	require.NoError(t, err)
 
 	if writeCommitConfig.branch != "" {
diff --git a/internal/git/gittest/objects.go b/internal/git/gittest/objects.go
index f6c8b4c64..aafca61b2 100644
--- a/internal/git/gittest/objects.go
+++ b/internal/git/gittest/objects.go
@@ -77,7 +77,7 @@ func WriteBlob(t testing.TB, cfg config.Cfg, testRepoPath string, contents []byt
 	hex := text.ChompBytes(ExecOpts(t, cfg, ExecConfig{Stdin: bytes.NewReader(contents)},
 		"-C", testRepoPath, "hash-object", "-w", "--stdin",
 	))
-	oid, err := NewObjectIDFromHex(hex)
+	oid, err := DefaultObjectHash.FromHex(hex)
 	require.NoError(t, err)
 	return oid
 }
diff --git a/internal/git/gittest/ref.go b/internal/git/gittest/ref.go
index e413ed9f5..9d9687089 100644
--- a/internal/git/gittest/ref.go
+++ b/internal/git/gittest/ref.go
@@ -18,7 +18,7 @@ func WriteRef(t testing.TB, cfg config.Cfg, repoPath string, ref git.ReferenceNa
 func ResolveRevision(t testing.TB, cfg config.Cfg, repoPath string, revision string) git.ObjectID {
 	t.Helper()
 	output := Exec(t, cfg, "-C", repoPath, "rev-parse", "--verify", revision)
-	objectID, err := NewObjectIDFromHex(text.ChompBytes(output))
+	objectID, err := DefaultObjectHash.FromHex(text.ChompBytes(output))
 	require.NoError(t, err)
 	return objectID
 }
diff --git a/internal/git/gittest/sha1.go b/internal/git/gittest/sha1.go
index 3cfb3dc26..4a5d8de33 100644
--- a/internal/git/gittest/sha1.go
+++ b/internal/git/gittest/sha1.go
@@ -4,14 +4,9 @@ package gittest
 
 import "gitlab.com/gitlab-org/gitaly/v15/internal/git"
 
-// EmptyTreeOID is the Git tree object hash that corresponds to an empty tree (directory)
-var EmptyTreeOID = git.ObjectHashSHA1.EmptyTreeOID
+var (
+	// DefaultObjectHash is the default hash used for running tests.
+	DefaultObjectHash = git.ObjectHashSHA1
 
-var initRepoExtraArgs = []string{}
-
-// NewObjectIDFromHex constructs a new ObjectID from the given hex
-// representation of the object ID. Returns ErrInvalidObjectID if the given
-// OID is not valid.
-func NewObjectIDFromHex(hex string) (git.ObjectID, error) {
-	return git.ObjectHashSHA1.FromHex(hex)
-}
+	initRepoExtraArgs = []string{}
+)
diff --git a/internal/git/gittest/sha256.go b/internal/git/gittest/sha256.go
index ad69cd981..d571657a9 100644
--- a/internal/git/gittest/sha256.go
+++ b/internal/git/gittest/sha256.go
@@ -4,19 +4,11 @@ package gittest
 
 import (
 	"gitlab.com/gitlab-org/gitaly/v15/internal/git"
-	"gitlab.com/gitlab-org/gitaly/v15/internal/git/sha256"
 )
 
-const (
-	// EmptyTreeOID is the Git tree object hash that corresponds to an empty tree (directory)
-	EmptyTreeOID = sha256.EmptyTreeOID
-)
-
-var initRepoExtraArgs = []string{"--object-format=sha256"}
+var (
+	// DefaultObjectHash is the default hash used for running tests.
+	DefaultObjectHash = git.ObjectHashSHA256
 
-// NewObjectIDFromHex constructs a new ObjectID from the given hex
-// representation of the object ID. Returns ErrInvalidObjectID if the given
-// OID is not valid.
-func NewObjectIDFromHex(hex string) (git.ObjectID, error) {
-	return sha256.NewObjectIDFromHex(hex)
-}
+	initRepoExtraArgs = []string{"--object-format=sha256"}
+)
diff --git a/internal/git/gittest/tag.go b/internal/git/gittest/tag.go
index bc03b17b4..09cfa2f5d 100644
--- a/internal/git/gittest/tag.go
+++ b/internal/git/gittest/tag.go
@@ -64,7 +64,7 @@ func WriteTag(
 
 	tagID := Exec(t, cfg, "-C", repoPath, "show-ref", "-s", tagName)
 
-	objectID, err := NewObjectIDFromHex(text.ChompBytes(tagID))
+	objectID, err := DefaultObjectHash.FromHex(text.ChompBytes(tagID))
 	require.NoError(t, err)
 
 	return objectID
diff --git a/internal/git/gittest/tree.go b/internal/git/gittest/tree.go
index 8ff19779a..7b93c996f 100644
--- a/internal/git/gittest/tree.go
+++ b/internal/git/gittest/tree.go
@@ -55,7 +55,7 @@ func RequireTree(t testing.TB, cfg config.Cfg, repoPath, treeish string, expecte
 
 			path := string(tabSplit[1])
 
-			objectID, err := NewObjectIDFromHex(string(spaceSplit[2]))
+			objectID, err := DefaultObjectHash.FromHex(string(spaceSplit[2]))
 			require.NoError(t, err)
 
 			actualEntries = append(actualEntries, TreeEntry{
@@ -107,7 +107,7 @@ func WriteTree(t testing.TB, cfg config.Cfg, repoPath string, entries []TreeEntr
 	stdout := ExecOpts(t, cfg, ExecConfig{Stdin: &tree},
 		"-C", repoPath, "mktree", "-z", "--missing",
 	)
-	treeOID, err := NewObjectIDFromHex(text.ChompBytes(stdout))
+	treeOID, err := DefaultObjectHash.FromHex(text.ChompBytes(stdout))
 	require.NoError(t, err)
 
 	return treeOID