diff --git a/integration_contract_test.go b/integration_contract_test.go
new file mode 100644
index 0000000..10a4812
--- /dev/null
+++ b/integration_contract_test.go
@@ -0,0 +1,99 @@
+package flashduty
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+)
+
+func TestIntegrationResponseContract(t *testing.T) {
+	for _, tc := range []struct {
+		name   string
+		target any
+		body   string
+	}{
+		{"list item", new(IntegrationItem), `{"integration_id":42,"plugin_id":9,"account_id":100,"data_source_id":42,"exclusive_data_source_id":0,"integration_key":"test-key","settings":{"password":"test-password"},"editable":true,"creator_id":11,"updated_by":12,"no_editable":false}`},
+		{"detail", new(IntegrationDetail), `{"integration_id":42,"plugin_id":9,"integration_key":"test-key","settings":{"headers":{"Authorization":"test-token"}},"editable":true,"creator_id":11,"updated_by":12,"no_editable":false,"test":{"success":false,"message":"test connection failed"}}`},
+		{"create", new(CreateIntegrationResponse), `{"integration_id":42,"integration_key":"test-key","test":{"success":false,"message":"test connection failed"}}`},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := json.Unmarshal([]byte(tc.body), tc.target); err != nil {
+				t.Fatal(err)
+			}
+			encoded, err := json.Marshal(tc.target)
+			if err != nil {
+				t.Fatal(err)
+			}
+			var want, got map[string]any
+			if err := json.Unmarshal([]byte(tc.body), &want); err != nil {
+				t.Fatal(err)
+			}
+			if err := json.Unmarshal(encoded, &got); err != nil {
+				t.Fatal(err)
+			}
+			for field, value := range want {
+				if !reflect.DeepEqual(got[field], value) {
+					t.Errorf("%s lost or changed: got %#v, want %#v", field, got[field], value)
+				}
+			}
+		})
+	}
+}
+
+func TestIntegrationResponsePreservesAbsentTest(t *testing.T) {
+	for _, tc := range []struct {
+		name   string
+		target any
+	}{
+		{"detail", new(IntegrationDetail)},
+		{"create", new(CreateIntegrationResponse)},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := json.Unmarshal([]byte(`{"integration_id":42}`), tc.target); err != nil {
+				t.Fatal(err)
+			}
+			encoded, err := json.Marshal(tc.target)
+			if err != nil {
+				t.Fatal(err)
+			}
+			var got map[string]any
+			if err := json.Unmarshal(encoded, &got); err != nil {
+				t.Fatal(err)
+			}
+			if _, ok := got["test"]; ok {
+				t.Fatalf("absent test result became %s", encoded)
+			}
+		})
+	}
+}
+
+func TestIntegrationRequestContract(t *testing.T) {
+	for _, tc := range []struct {
+		name   string
+		target any
+		body   string
+	}{
+		{"create", new(CreateIntegrationRequest), `{"plugin_type":"standard.alert","integration_key":"0123456789abcdef0123456789abcdef100","is_test":true,"settings":{"headers":{}}}`},
+		{"update", new(UpdateIntegrationRequest), `{"integration_id":42,"team_id":0,"is_test":true,"settings":{"headers":{}}}`},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := json.Unmarshal([]byte(tc.body), tc.target); err != nil {
+				t.Fatal(err)
+			}
+			encoded, err := json.Marshal(tc.target)
+			if err != nil {
+				t.Fatal(err)
+			}
+			var want, got map[string]any
+			if err := json.Unmarshal([]byte(tc.body), &want); err != nil {
+				t.Fatal(err)
+			}
+			if err := json.Unmarshal(encoded, &got); err != nil {
+				t.Fatal(err)
+			}
+			if !reflect.DeepEqual(got, want) {
+				t.Fatalf("request fields lost: got %s, want %s", encoded, tc.body)
+			}
+		})
+	}
+}