Fix decoding null for NullableString

While at it, also fix golangci-lint errors, and add tests to make sure
the NullableTime are able to decode null time, too.

json.go

@@ -19,14 +19,14 @@ func (ns *NullableString) UnmarshalJSON(b []byte) error {
 	str := string(b)
 	// Special case when we encounter `null`, modify it to the empty string
 	if str == "null" || str == "" {
-		str = ""
-	} else {
-		unquoted, err := strconv.Unquote(str)
-		if err != nil {
-			return err
-		}
-		*ns = NullableString(unquoted)
+		*ns = ""
+		return nil
+	}
+	unquoted, err := strconv.Unquote(str)
+	if err != nil {
+		return err
 	}
+	*ns = NullableString(unquoted)
 
 	return nil
 }
@@ -105,7 +105,6 @@ func (nt *NullableTime) UnmarshalJSON(b []byte) error {
 		return err
 	}
 	if ns == "" {
-		nt = nil
 		return nil
 	}
 

json_test.go

@@ -0,0 +1,66 @@
+package otils
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+)
+
+func TestNullableString(t *testing.T) {
+	type testNullableString struct {
+		S NullableString
+	}
+	tests := []struct {
+		name     string
+		s        string
+		expected NullableString
+	}{
+		{"normal", `{"s": "foo"}`, NullableString("foo")},
+		{"null", `{"s": null}`, NullableString("")},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			tn := testNullableString{S: "init"}
+			if err := json.Unmarshal([]byte(tc.s), &tn); err != nil {
+				t.Error(err)
+			}
+			if tn.S != tc.expected {
+				t.Errorf("unexpected result, want: %q, got: %q", tc.expected, tn.S)
+			}
+		})
+	}
+}
+
+func TestNullableTime(t *testing.T) {
+	type testNullableTime struct {
+		T *NullableTime
+	}
+	now := NullableTime(time.Now())
+	tests := []struct {
+		name     string
+		s        string
+		isNull   bool
+		expected NullableTime
+	}{
+		{"null", `{"T": null}`, true, NullableTime(now)},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			tn := testNullableTime{T: &now}
+			if err := json.Unmarshal([]byte(tc.s), &tn); err != nil {
+				t.Error(err)
+			}
+			if tc.isNull && tn.T != nil {
+				t.Errorf("expected nil, got non-nil")
+			}
+			if !tc.isNull && time.Time(*tn.T).UnixNano() != time.Time(tc.expected).UnixNano() {
+				t.Errorf("unexpected result, want: %v, got: %v", tc.expected, *tn.T)
+			}
+		})
+	}
+}

otils_test.go

@@ -338,7 +338,7 @@ func TestCORSMiddleware(t *testing.T) {
 
 	for i, tt := range tests {
 		handler := otils.CORSMiddleware(tt.cors, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			w.Write([]byte("Hello!"))
+			_, _ = w.Write([]byte("Hello!"))
 		}))
 		tst := httptest.NewServer(handler)
 		res, err := tst.Client().Get(tst.URL)