time.Unix(0,0) does not return time.Time{} as one would expect. This …

…is a workaround so that a call Expiry.Time() returns an accurate representation of what the JWT expiry actually is

jwt/claims.go

@@ -73,6 +73,11 @@ func (n *NumericDate) UnmarshalJSON(b []byte) error {
 
 // Time returns time.Time representation of NumericDate.
 func (n NumericDate) Time() time.Time {
+	if n == NumericDate(0) {
+		// time.Unix(0,0) != time.Time{} (it should, but it doesn't).
+		// This is a workaround.
+		return time.Time{}
+	}
 	return time.Unix(int64(n), 0)
 }
 

jwt/claims_test.go

@@ -78,3 +78,32 @@ func TestDecodeClaims(t *testing.T) {
 		assert.Equal(t, v.Err, json.Unmarshal([]byte(v.Raw), &c))
 	}
 }
+
+func TestTime(t *testing.T) {
+	tests := []struct {
+		description string
+		input       NumericDate
+		expected    time.Time
+	}{
+		{
+			description: "0 returns time.Time{}",
+			input:       NumericDate(0),
+			expected:    time.Time{},
+		},
+		{
+			description: "Other number returns appropriate time",
+			input:       NumericDate(1547232324),
+			expected:    time.Date(2019, 1, 11, 18, 45, 24, 0, time.UTC),
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.description, func(t *testing.T) {
+			t.Parallel()
+
+			output := test.input.Time()
+			assert.Truef(t, test.expected.Equal(output), "Expected [%s] but received [%s]", test.expected, output)
+		})
+	}
+}