apitypes: omit PhaseResponse.End from JSON if empty (#274)

api/apitypes/apitypes.go

@@ -1,6 +1,7 @@
 package apitypes
 
 import (
+	"encoding/json"
 	"fmt"
 	"time"
 
@@ -34,6 +35,26 @@ type PhaseResponse struct {
 	Trial     bool               `json:"trial,omitempty"`
 }
 
+func (pr PhaseResponse) MarshalJSON() ([]byte, error) {
+	type Alias PhaseResponse
+	if pr.End.IsZero() {
+		return json.Marshal(&struct {
+			*Alias
+			End byte `json:"end,omitempty"`
+		}{
+			Alias: (*Alias)(&pr),
+		})
+	} else {
+		return json.Marshal(&struct {
+			*Alias
+			End time.Time `json:"end"`
+		}{
+			Alias: (*Alias)(&pr),
+			End:   pr.End,
+		})
+	}
+}
+
 type PaymentMethodsResponse struct {
 	Org            string           `json:"org"`
 	PaymentMethods []payment.Method `json:"methods"`

api/apitypes/json_test.go

@@ -0,0 +1,38 @@
+package apitypes
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+)
+
+func TestPhaseResponseJSON(t *testing.T) {
+	cases := []struct {
+		pr   PhaseResponse
+		want string
+	}{
+		{
+			pr:   PhaseResponse{},
+			want: `{"effective":"0001-01-01T00:00:00Z"}`,
+		},
+		{
+			pr: PhaseResponse{
+				End: time.Date(2018, 1, 1, 0, 0, 0, 0, time.UTC),
+			},
+			want: `{"effective":"0001-01-01T00:00:00Z","end":"2018-01-01T00:00:00Z"}`,
+		},
+	}
+
+	for _, tt := range cases {
+		t.Run("", func(t *testing.T) {
+			data, err := json.Marshal(tt.pr)
+			if err != nil {
+				t.Fatal(err)
+			}
+			got := string(data)
+			if got != tt.want {
+				t.Errorf("got = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}