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package gittest
import (
"crypto/rand"
"io"
"strings"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"gitlab.com/gitlab-org/gitaly/internal/git"
"gitlab.com/gitlab-org/gitaly/internal/gitaly/config"
)
// TestDeltaIslands is based on the tests in
// https://github.com/git/git/blob/master/t/t5320-delta-islands.sh .
func TestDeltaIslands(t *testing.T, cfg config.Cfg, repoPath string, repack func() error) {
t.Helper()
// Create blobs that we expect Git to use delta compression on.
blob1, err := io.ReadAll(io.LimitReader(rand.Reader, 100000))
require.NoError(t, err)
blob2 := append(blob1, "\nblob 2"...)
// Assume Git prefers the largest blob as the delta base.
badBlob := append(blob2, "\nbad blob"...)
blob1ID := commitBlob(t, cfg, repoPath, "refs/heads/branch1", blob1)
blob2ID := commitBlob(t, cfg, repoPath, "refs/tags/tag2", blob2)
// The bad blob will only be reachable via a non-standard ref. Because of
// that it should be excluded from delta chains in the main island.
badBlobID := commitBlob(t, cfg, repoPath, "refs/bad/ref3", badBlob)
// So far we have create blobs and commits but they will be in loose
// object files; we want them to be delta compressed. Run repack to make
// that happen.
Exec(t, cfg, "-C", repoPath, "repack", "-ad")
assert.Equal(t, badBlobID, deltaBase(t, cfg, repoPath, blob1ID), "expect blob 1 delta base to be bad blob after test setup")
assert.Equal(t, badBlobID, deltaBase(t, cfg, repoPath, blob2ID), "expect blob 2 delta base to be bad blob after test setup")
require.NoError(t, repack(), "repack after delta island setup")
assert.Equal(t, blob2ID, deltaBase(t, cfg, repoPath, blob1ID), "blob 1 delta base should be blob 2 after repack")
// blob2 is the bigger of the two so it should be the delta base
assert.Equal(t, git.ZeroOID.String(), deltaBase(t, cfg, repoPath, blob2ID), "blob 2 should not be delta compressed after repack")
}
func commitBlob(t *testing.T, cfg config.Cfg, repoPath, ref string, content []byte) string {
blobID := WriteBlob(t, cfg, repoPath, content)
// No parent, that means this will be an initial commit. Not very
// realistic but it doesn't matter for delta compression.
commitID := WriteCommit(t, cfg, repoPath,
WithTreeEntries(TreeEntry{
Mode: "100644", OID: blobID, Path: "file",
}),
WithParents(),
)
Exec(t, cfg, "-C", repoPath, "update-ref", ref, commitID.String())
return blobID.String()
}
func deltaBase(t *testing.T, cfg config.Cfg, repoPath string, blobID string) string {
catfileOut := ExecOpts(t, cfg, ExecConfig{Stdin: strings.NewReader(blobID)},
"-C", repoPath, "cat-file", "--batch-check=%(deltabase)",
)
return chompToString(catfileOut)
}
func chompToString(s []byte) string { return strings.TrimSuffix(string(s), "\n") }
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