oidc: add test case to reproduce #203

Running the tests will always result in a nil pointer
dereference on UserInfoAddress.

pkg/oidc/userinfo_test.go

@@ -81,3 +81,35 @@ func TestUserInfoEmailVerifiedUnmarshal(t *testing.T) {
 		}, uie)
 	})
 }
+
+// issue 203 test case.
+func Test_userinfo_GetAddress_issue_203(t *testing.T) {
+	tests := []struct {
+		name string
+		data string
+	}{
+		{
+			name: "with address",
+			data: `{"address":{"street_address":"Test 789\nPostfach 2"},"email":"test","email_verified":true,"name":"Test","phone_number":"0791234567","phone_number_verified":true,"private_claim":"test","sub":"test"}`,
+		},
+		{
+			name: "without address",
+			data: `{"email":"test","email_verified":true,"name":"Test","phone_number":"0791234567","phone_number_verified":true,"private_claim":"test","sub":"test"}`,
+		},
+		{
+			name: "null address",
+			data: `{"address":null,"email":"test","email_verified":true,"name":"Test","phone_number":"0791234567","phone_number_verified":true,"private_claim":"test","sub":"test"}`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			info := &userinfo{}
+			if err := json.Unmarshal([]byte(tt.data), info); err != nil {
+				t.Fatal(err)
+			}
+
+			info.GetAddress().GetCountry() //<- used to panic
+		})
+	}
+}