Adds Available

this is the database for available packages

available.go

@@ -0,0 +1,40 @@
+package pm
+
+import (
+	"github.com/pkg/errors"
+)
+
+// Name exists to document the keys in Available
+type Name string
+
+// Version exists to document the keys in Available
+type Version string
+
+// Available is the structure used to represent the collection of all packages
+// that can be installed.
+type Available map[Name]map[Version]Meta
+
+// Add inserts m into a.
+func (a Available) Add(m Meta) error {
+	if _, err := m.Valid(); err != nil {
+		return errors.Wrap(err, "invalid meta")
+	}
+
+	if _, ok := a[Name(m.Name)]; !ok {
+		a[m.Name] = map[Version]Meta{}
+	}
+	a[m.Name][m.Version] = m
+	return nil
+}
+
+// Update inserts all data from o into a.
+func (a Available) Update(o Available) error {
+	for _, vers := range o {
+		for _, m := range vers {
+			if err := a.Add(m); err != nil {
+				return errors.Wrap(err, "adding")
+			}
+		}
+	}
+	return nil
+}

available_test.go

@@ -0,0 +1,95 @@
+package pm
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestAvailableAdd(t *testing.T) {
+
+	tests := []struct {
+		label string
+		m     Meta
+		count int
+		err   error
+	}{
+		{
+			label: "good",
+			m:     Meta{Name: "a", Version: "v1.0.0", Description: "test"},
+			count: 1,
+		},
+		{
+			label: "bad meta",
+			m:     Meta{Name: "a"},
+			count: 1,
+			err:   errors.New("missing"),
+		},
+		{
+			label: "dupe is last in",
+			m:     Meta{Name: "a", Version: "v1.0.0", Description: "better version"},
+			count: 1,
+		},
+		{
+			label: "another good",
+			m:     Meta{Name: "a", Version: "v1.0.0", Description: "better version"},
+			count: 1,
+		},
+	}
+
+	a := Available{}
+	for _, test := range tests {
+		t.Run(test.label, func(t *testing.T) {
+			if err := a.Add(test.m); (err == nil) != (test.err == nil) {
+				t.Fatalf("adding meta%v", err)
+			}
+
+			if got, want := len(a), test.count; got != want {
+				t.Fatalf("unexpected length after Add: got %v, want %v", got, want)
+			}
+		})
+	}
+
+	if got, want := a["a"]["v1.0.0"].Description, "better version"; got != want {
+		t.Fatalf("version: got %v, want %v", got, want)
+	}
+}
+
+func TestAvailableUpdate(t *testing.T) {
+	a := Available{}
+	if err := a.Add(Meta{Name: "a", Version: "v1.0.0", Description: "test"}); err != nil {
+		t.Fatalf("add: %v", err)
+	}
+	if err := a.Add(Meta{Name: "b", Version: "v2.0.0", Description: "test"}); err != nil {
+		t.Fatalf("add: %v", err)
+	}
+
+	b := Available{}
+	a.Update(b)
+	if got, want := len(a), 2; got != want {
+		t.Fatalf("len after empty update: got %v, want %v", got, want)
+	}
+
+	if err := b.Add(Meta{Name: "a", Version: "v1.0.0", Description: "test last in"}); err != nil {
+		t.Fatalf("add: %v", err)
+	}
+	if err := b.Add(Meta{Name: "b", Version: "v2.1.0", Description: "test"}); err != nil {
+		t.Fatalf("add: %v", err)
+	}
+
+	if err := a.Update(b); err != nil {
+		t.Fatalf("update: %v", err)
+	}
+	if got, want := len(a), 2; got != want {
+		t.Fatalf("len after update: got %v, want %v", got, want)
+	}
+	if got, want := len(a["a"]), 1; got != want {
+		t.Fatalf("len after update: got %v, want %v", got, want)
+	}
+	if got, want := len(a["b"]), 2; got != want {
+		t.Fatalf("len after update: got %v, want %v", got, want)
+	}
+
+	if got, want := a["a"]["v1.0.0"].Description, "test last in"; got != want {
+		t.Fatalf("last in didn't override")
+	}
+}

meta.go

@@ -3,10 +3,10 @@ package pm
 import "errors"
 
 type Meta struct {
-	Name        string `json:"name"`
-	Version     string `json:"version"`
-	Description string `json:"description"`
-	Namespace   string `json:"namespace"`
+	Name        Name    `json:"name"`
+	Version     Version `json:"version"`
+	Description string  `json:"description"`
+	Namespace   string  `json:"namespace"`
 }
 
 func (m *Meta) Valid() (bool, error) {