diff --git a/src/__tests__/modification.spec.ts b/src/__tests__/modification.spec.ts
new file mode 100644
index 0000000..1e6ea44
--- /dev/null
+++ b/src/__tests__/modification.spec.ts
@@ -0,0 +1,150 @@
+/*
+ *                       ######
+ *                       ######
+ * ############    ####( ######  #####. ######  ############   ############
+ * #############  #####( ######  #####. ######  #############  #############
+ *        ######  #####( ######  #####. ######  #####  ######  #####  ######
+ * ###### ######  #####( ######  #####. ######  #####  #####   #####  ######
+ * ###### ######  #####( ######  #####. ######  #####          #####  ######
+ * #############  #############  #############  #############  #####  ######
+ *  ############   ############  #############   ############  #####  ######
+ *                                      ######
+ *                               #############
+ *                               ############
+ * Adyen NodeJS API Library
+ * Copyright (c) 2020 Adyen B.V.
+ * This file is open source and available under the MIT license.
+ * See the LICENSE file for more info.
+ */
+
+import nock from "nock";
+import { createClient } from "../__mocks__/base";
+import Modification from "../services/modification";
+import Client from "../client";
+
+const modificationResult: IPayouts.ModifyResponse = {
+    pspReference: "1234567890987654",
+    response: "[refund-received]"
+};
+
+const createModificationRequest = (): IPayments.ModificationRequest => {
+    return {
+        merchantAccount: process.env.ADYEN_MERCHANT!,
+        originalReference: "862615382016087C",
+        modificationAmount: {
+            value: 500 ,
+            currency: "EUR"
+        }
+    };
+};
+
+const createCancelRequest = (): IPayments.ModificationRequest => {
+    return {
+        merchantAccount: process.env.ADYEN_MERCHANT!,
+        originalReference: "862615382016087C"
+    };
+};
+const isCI = process.env.CI === "true" || (typeof process.env.CI === "boolean" && process.env.CI);
+
+let client: Client;
+let modification: Modification;
+let scope: nock.Scope;
+
+beforeEach((): void => {
+    if (!nock.isActive()) {
+        nock.activate();
+    }
+    client = createClient();
+    modification = new Modification(client);
+    scope = nock(`${client.config.endpoint}/pal/servlet/Payment/${Client.API_VERSION}`);
+});
+
+afterEach(() => {
+    nock.cleanAll();
+});
+
+describe("Modification", (): void => {
+    test.each([isCI, true])("should perform a refund, isMock: %p", async (isMock): Promise<void> => {
+        !isMock && nock.restore();
+        scope.post("/refund")
+            .reply(200, modificationResult);
+
+        const request = createModificationRequest();
+        try {
+            const result = await modification.refund(request);
+            expect(result).toBeTruthy();
+        } catch (e) {
+            fail(e.message);
+        }
+    });
+
+    test.each([isCI, true])("should perform a capture, isMock: %p", async (isMock): Promise<void> => {
+        !isMock && nock.restore();
+        scope.post("/capture")
+            .reply(200, modificationResult);
+
+        const request = createModificationRequest();
+        try {
+            const result = await modification.capture(request);
+            expect(result).toBeTruthy();
+        } catch (e) {
+            fail(e.message);
+        }
+    });
+
+    test.each([isCI, true])("should perform a cancelOrRefund, isMock: %p", async (isMock): Promise<void> => {
+        !isMock && nock.restore();
+        scope.post("/cancelOrRefund")
+            .reply(200, modificationResult);
+
+        const request = createCancelRequest();
+        try {
+            const result = await modification.cancelOrRefund(request);
+            expect(result).toBeTruthy();
+        } catch (e) {
+            fail(e.message);
+        }
+    });
+
+    test.each([isCI, true])("should perform a cancel, isMock: %p", async (isMock): Promise<void> => {
+        !isMock && nock.restore();
+        scope.post("/cancel")
+            .reply(200, modificationResult);
+
+        const request = createCancelRequest();
+        try {
+            const result = await modification.cancel(request);
+            expect(result).toBeTruthy();
+        } catch (e) {
+            fail(e.message);
+        }
+    });
+
+    test.each([isCI, true])("should perform a technicalCancel, isMock: %p", async (isMock): Promise<void> => {
+        !isMock && nock.restore();
+        scope.post("/technicalCancel")
+            .reply(200, modificationResult);
+
+        const request = createCancelRequest();
+        try {
+            const result = await modification.technicalCancel(request);
+            expect(result).toBeTruthy();
+        } catch (e) {
+            fail(e.message);
+        }
+    });
+
+    test.each([isCI, true])("should perform a adjustAuthorisation, isMock: %p", async (isMock): Promise<void> => {
+        !isMock && nock.restore();
+        scope.post("/adjustAuthorisation")
+            .reply(200, modificationResult);
+
+        const request = createModificationRequest();
+        try {
+            const result = await modification.adjustAuthorisation(request);
+            expect(result).toBeTruthy();
+        } catch (e) {
+            fail(e.message);
+        }
+    });
+});