organize essential APIs into platform, workflow and pkg folders (#337)

Add more logic to the way code is organized.

	/pkg -- library code not directly connected to micromdm
	/mdm -- packages meant for the services devices interract with. The MDM protocol.
	/dep -- DEP API and related packages.
	/platform -- Core APIs the server provides. Commands API, Devices API, queue, pubsub etc.
	/workflow -- Packages/API that build on top of platform. Today that's the webhook package.
		     Depending on what ends up here, the workflow folder might become its own repository.

platform/command/command_test.go

@@ -0,0 +1,103 @@
+package command
+
+import (
+	"context"
+	"errors"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/boltdb/bolt"
+	"github.com/micromdm/mdm"
+)
+
+func TestService_NewCommand(t *testing.T) {
+	svc := setupDB(t)
+	mock := &mockPublisher{}
+	svc.publisher = mock
+	passPublisher := func(string, []byte) error { return nil }
+	failPublisher := func(string, []byte) error {
+		return errors.New("failed")
+	}
+
+	tests := []struct {
+		name      string
+		publisher func(string, []byte) error
+		request   *mdm.CommandRequest
+		wantErr   bool
+	}{
+		{
+			name:      "happy path",
+			wantErr:   false,
+			publisher: passPublisher,
+			request: &mdm.CommandRequest{
+				UDID: "foobarbaz",
+				Command: mdm.Command{
+					RequestType: "DeviceInformation",
+					DeviceInformation: mdm.DeviceInformation{
+						Queries: []string{"foo", "bar", "baz"},
+					},
+				},
+			},
+		},
+		{
+			name:      "publish fail",
+			wantErr:   true,
+			publisher: failPublisher,
+			request: &mdm.CommandRequest{
+				Command: mdm.Command{
+					RequestType: "DeviceInformation",
+				},
+			},
+		},
+		{
+			name:      "empty request",
+			wantErr:   true,
+			publisher: passPublisher,
+		},
+		{
+			name:      "bad payload",
+			wantErr:   true,
+			publisher: passPublisher,
+			request: &mdm.CommandRequest{
+				UDID: "foobarbaz",
+				Command: mdm.Command{
+					RequestType: "DevicePropaganda",
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		mock.PublishFn = tt.publisher
+		_, err := svc.NewCommand(context.Background(), tt.request)
+		if (err != nil) != tt.wantErr {
+			t.Errorf("%q. CommandService.NewCommand() error = %v, wantErr %v",
+				tt.name, err, tt.wantErr)
+			continue
+		}
+	}
+}
+
+type mockPublisher struct {
+	PublishFn func(string, []byte) error
+}
+
+func (m *mockPublisher) Publish(ctx context.Context, s string, b []byte) error {
+	return m.PublishFn(s, b)
+}
+
+func setupDB(t *testing.T) *Command {
+	f, _ := ioutil.TempFile("", "bolt-")
+	f.Close()
+	os.Remove(f.Name())
+
+	db, err := bolt.Open(f.Name(), 0777, nil)
+	if err != nil {
+		t.Fatalf("couldn't open bolt, err %s\n", err)
+	}
+	svc, err := New(db, nil)
+	if err != nil {
+		t.Fatalf("couldn't create service, err %s\n", err)
+	}
+	return svc
+}