4 files changed, 135 insertions, 17 deletions
diff --git a/librsync/common_test.go b/librsync/common_test.go
new file mode 100644
index 0000000..35d59b1
--- /dev/null
+++ b/librsync/common_test.go
@@ -0,0 +1,24 @@
+package librsync
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+// Some functions to support testing
+
+func dump(r io.Reader) (string, error) {
+	path := fmt.Sprintf("%s%cgolibrsync_test", os.TempDir(), os.PathSeparator)
+	file, err := os.Create(path)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	if _, err = io.Copy(file, r); err != nil {
+		return "", err
+	}
+
+	return path, nil
+}
diff --git a/librsync/helpers.go b/librsync/helpers.go
new file mode 100644
index 0000000..e560275
--- /dev/null
+++ b/librsync/helpers.go
@@ -0,0 +1,73 @@
+package librsync
+
+import (
+	"io"
+)
+
+// Some helper functions to make things more convenient.
+
+// CreateSignature wraps around a signature generation job and copies the result to the signature writer.
+func CreateSignature(basis io.Reader, signature io.Writer) error {
+	siggen, err := NewDefaultSignatureGen(basis)
+	if err != nil {
+		return err
+	}
+	defer siggen.Close()
+
+	_, err = io.Copy(signature, siggen)
+	return err
+}
+
+// CreateDelta wraps around a delta generation job and copies the result to the delta writer.
+func CreateDelta(signature, newfile io.Reader, delta io.Writer) error {
+	sig, err := LoadSignature(signature)
+	if err != nil {
+		return err
+	}
+	defer sig.Close()
+
+	deltagen, err := NewDeltaGen(sig, newfile)
+	if err != nil {
+		return err
+	}
+	defer deltagen.Close()
+
+	_, err = io.Copy(delta, deltagen)
+	return err
+}
+
+// InstantDelta creates a delta file without the extra step of creating a signature.
+func InstantDelta(basis, newfile io.Reader, delta io.Writer) error {
+	siggen, err := NewDefaultSignatureGen(basis)
+	if err != nil {
+		return err
+	}
+	defer siggen.Close()
+
+	sig, err := LoadSignature(siggen)
+	if err != nil {
+		return err
+	}
+	defer sig.Close()
+
+	deltagen, err := NewDeltaGen(sig, newfile)
+	if err != nil {
+		return err
+	}
+	defer deltagen.Close()
+
+	_, err = io.Copy(delta, deltagen)
+	return err
+}
+
+// Patch wraps around a Patcher job and copies the result to newfile.
+func Patch(basis io.ReaderAt, delta io.Reader, newfile io.Writer) error {
+	patcher, err := NewPatcher(delta, basis)
+	if err != nil {
+		return err
+	}
+	defer patcher.Close()
+
+	_, err = io.Copy(newfile, patcher)
+	return err
+}
diff --git a/librsync/helpers_test.go b/librsync/helpers_test.go
new file mode 100644
index 0000000..c12992f
--- /dev/null
+++ b/librsync/helpers_test.go
@@ -0,0 +1,38 @@
+package librsync
+
+import (
+	"bytes"
+	"github.com/kch42/golibrsync/librsync/testdata"
+	"testing"
+)
+
+func TestHelpers(t *testing.T) {
+	basis := bytes.NewReader(testdata.RandomData())
+	mutation := bytes.NewReader(testdata.Mutation())
+
+	delta := new(bytes.Buffer)
+	if err := InstantDelta(basis, mutation, delta); err != nil {
+		t.Fatalf("InstantDelta failed: %s", err)
+	}
+
+	if !bytes.Equal(delta.Bytes(), testdata.Delta()) {
+		if path, err := dump(delta); err == nil {
+			t.Fatalf("Deltas do not match. Generated delta dumped to %s", path)
+		} else {
+			t.Fatalf("Deltas do not match. Could not dump delta: %s", err)
+		}
+	}
+
+	newfile := new(bytes.Buffer)
+	if err := Patch(basis, delta, newfile); err != nil {
+		t.Fatalf("Patch failed: %s", err)
+	}
+
+	if !bytes.Equal(newfile.Bytes(), testdata.Mutation()) {
+		if path, err := dump(newfile); err == nil {
+			t.Fatalf("patch result and mutation are not equal. Result dumped to %s", path)
+		} else {
+			t.Fatalf("patch result and mutation are not equal. Could not dump result: %s", err)
+		}
+	}
+}
diff --git a/librsync/librsync_test.go b/librsync/librsync_test.go
index e0fd50f..256e344 100644
--- a/librsync/librsync_test.go
+++ b/librsync/librsync_test.go
@@ -2,28 +2,11 @@ package librsync
 
 import (
 	"bytes"
-	"fmt"
 	"github.com/kch42/golibrsync/librsync/testdata"
 	"io"
-	"os"
 	"testing"
 )
 
-func dump(r io.Reader) (string, error) {
-	path := fmt.Sprintf("%s%cgolibrsync_test", os.TempDir(), os.PathSeparator)
-	file, err := os.Create(path)
-	if err != nil {
-		return "", err
-	}
-	defer file.Close()
-
-	if _, err = io.Copy(file, r); err != nil {
-		return "", err
-	}
-
-	return path, nil
-}
-
 func TestSignatureDeltaPatch(t *testing.T) {
 	// Generate signature
 	orig := bytes.NewReader(testdata.RandomData())