Add basic Lock implementation (#5)

lock.go

@@ -0,0 +1,84 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+
+	"github.com/sdboyer/gps"
+)
+
+type Lock struct {
+	Memo []byte
+	P    []gps.LockedProject
+}
+
+type rawLock struct {
+	Memo string      `json:"memo"`
+	P    []lockedDep `json:"projects"`
+}
+
+type lockedDep struct {
+	Name       string   `json:"name"`
+	Version    string   `json:"version,omitempty"`
+	Branch     string   `json:"branch,omitempty"`
+	Revision   string   `json:"revision"`
+	Repository string   `json:"repo,omitempty"`
+	Packages   []string `json:"packages"`
+}
+
+func ReadLock(r io.Reader) (*Lock, error) {
+	rl := rawLock{}
+	err := json.NewDecoder(r).Decode(&rl)
+	if err != nil {
+		return nil, err
+	}
+
+	b, err := hex.DecodeString(rl.Memo)
+	if err != nil {
+		return nil, fmt.Errorf("invalid hash digest in lock's memo field")
+	}
+	l := &Lock{
+		Memo: b,
+		P:    make([]gps.LockedProject, len(rl.P)),
+	}
+
+	for i, ld := range rl.P {
+		r := gps.Revision(ld.Revision)
+
+		var v gps.Version
+		if ld.Version != "" {
+			if ld.Branch != "" {
+				return nil, fmt.Errorf("lock file specified both a branch (%s) and version (%s) for %s", ld.Branch, ld.Version, ld.Name)
+			}
+			v = gps.NewVersion(ld.Version).Is(r)
+		} else if ld.Branch != "" {
+			v = gps.NewBranch(ld.Branch).Is(r)
+		} else if r == "" {
+			return nil, fmt.Errorf("lock file has entry for %s, but specifies no version", ld.Name)
+		} else {
+			v = r
+		}
+
+		id := gps.ProjectIdentifier{
+			ProjectRoot: gps.ProjectRoot(ld.Name),
+			NetworkName: ld.Repository,
+		}
+		l.P[i] = gps.NewLockedProject(id, v, ld.Packages)
+	}
+
+	return l, nil
+}
+
+func (l *Lock) InputHash() []byte {
+	return l.Memo
+}
+
+func (l *Lock) Projects() []gps.LockedProject {
+	return l.P
+}

lock_test.go

@@ -0,0 +1,68 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"encoding/hex"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/sdboyer/gps"
+)
+
+func TestReadLock(t *testing.T) {
+	const le = `{
+    "memo": "2252a285ab27944a4d7adcba8dbd03980f59ba652f12db39fa93b927c345593e",
+    "projects": [
+        {
+            "name": "github.com/sdboyer/gps",
+            "branch": "master",
+			"version": "v0.12.0",
+            "revision": "d05d5aca9f895d19e9265839bffeadd74a2d2ecb",
+            "packages": ["."]
+        }
+    ]
+}`
+	const lg = `{
+    "memo": "2252a285ab27944a4d7adcba8dbd03980f59ba652f12db39fa93b927c345593e",
+    "projects": [
+        {
+            "name": "github.com/sdboyer/gps",
+            "branch": "master",
+            "revision": "d05d5aca9f895d19e9265839bffeadd74a2d2ecb",
+            "packages": ["."]
+        }
+    ]
+}`
+
+	_, err := ReadLock(strings.NewReader(le))
+	if err == nil {
+		t.Error("Reading lock with invalid props should have caused error, but did not")
+	} else if !strings.Contains(err.Error(), "both a branch") {
+		t.Errorf("Unexpected error %q; expected multiple version error", err)
+	}
+
+	l, err := ReadLock(strings.NewReader(lg))
+	if err != nil {
+		t.Fatalf("Should have read Lock correctly, but got err %q", err)
+	}
+
+	b, _ := hex.DecodeString("2252a285ab27944a4d7adcba8dbd03980f59ba652f12db39fa93b927c345593e")
+	l2 := &Lock{
+		Memo: b,
+		P: []gps.LockedProject{
+			gps.NewLockedProject(
+				gps.ProjectIdentifier{ProjectRoot: gps.ProjectRoot("github.com/sdboyer/gps")},
+				gps.NewBranch("master").Is(gps.Revision("d05d5aca9f895d19e9265839bffeadd74a2d2ecb")),
+				[]string{"."},
+			),
+		},
+	}
+
+	if !reflect.DeepEqual(l, l2) {
+		t.Error("Valid lock did not parse as expected")
+	}
+}