snapshot: rename layer manipulator to snapshot

Signed-off-by: Stephen J Day <stephen.day@docker.com>

snapshot/manager_test.go

@@ -0,0 +1,111 @@
+package snapshot
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// TestSnapshotManagerBasic implements something similar to the conceptual
+// examples we've discussed thus far. It does perform mounts, so you must run
+// as root.
+func TestSnapshotManagerBasic(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", "test-layman-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// defer os.RemoveAll(tmpDir)
+
+	root := filepath.Join(tmpDir, "root")
+
+	lm, err := NewManager(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	preparing := filepath.Join(tmpDir, "preparing")
+	if err := os.MkdirAll(preparing, 0777); err != nil {
+		t.Fatal(err)
+	}
+
+	mounts, err := lm.Prepare(preparing, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(mounts) < 1 {
+		t.Fatal("expected mounts to have entries")
+	}
+
+	for _, mount := range mounts {
+		if !strings.HasPrefix(mount.Target, preparing) {
+			t.Fatalf("expected mount target to be prefixed with tmpDir: %q does not startwith %q", mount.Target, preparing)
+		}
+
+		t.Log(MountCommand(mount))
+	}
+
+	if err := MountAll(mounts...); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := ioutil.WriteFile(filepath.Join(preparing, "foo"), []byte("foo\n"), 0777); err != nil {
+		t.Fatal(err)
+	}
+
+	os.MkdirAll(preparing+"/a/b/c", 0755)
+
+	// defer os.Remove(filepath.Join(tmpDir, "foo"))
+
+	committed := filepath.Join(lm.root, "committed")
+
+	if err := lm.Commit(committed, preparing); err != nil {
+		t.Fatal(err)
+	}
+
+	if lm.Parent(preparing) != "" {
+		t.Fatalf("parent of new layer should be empty, got lm.Parent(%q) == %q", preparing, lm.Parent(preparing))
+	}
+
+	next := filepath.Join(tmpDir, "nextlayer")
+	if err := os.MkdirAll(next, 0777); err != nil {
+		t.Fatal(err)
+	}
+
+	mounts, err = lm.Prepare(next, committed)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := MountAll(mounts...); err != nil {
+		t.Fatal(err)
+	}
+
+	for _, mount := range mounts {
+		if !strings.HasPrefix(mount.Target, next) {
+			t.Fatalf("expected mount target to be prefixed with tmpDir: %q does not startwith %q", mount.Target, next)
+		}
+
+		t.Log(MountCommand(mount))
+	}
+
+	if err := ioutil.WriteFile(filepath.Join(next, "bar"), []byte("bar\n"), 0777); err != nil {
+		t.Fatal(err)
+	}
+
+	// also, change content of foo to bar
+	if err := ioutil.WriteFile(filepath.Join(next, "foo"), []byte("bar\n"), 0777); err != nil {
+		t.Fatal(err)
+	}
+
+	os.RemoveAll(next + "/a/b")
+	nextCommitted := filepath.Join(lm.root, "committed-next")
+	if err := lm.Commit(nextCommitted, next); err != nil {
+		t.Fatal(err)
+	}
+
+	if lm.Parent(nextCommitted) != committed {
+		t.Fatalf("parent of new layer should be %q, got lm.Parent(%q) == %q (%#v)", committed, next, lm.Parent(next), lm.parents)
+	}
+}