diff --git a/src/modules/login/Login.test.tsx b/src/modules/login/Login.test.tsx
index 5a00b17..7a579e5 100644
--- a/src/modules/login/Login.test.tsx
+++ b/src/modules/login/Login.test.tsx
@@ -1,6 +1,8 @@
 import { fireEvent, waitFor, type RenderResult } from '@testing-library/react-native';
 import React from 'react';
 
+import * as api from '@/api';
+import { ApiError } from '@/errors';
 import Login from '@/modules/login/Login';
 import { renderWithProviders } from '@/testUtils';
 
@@ -12,8 +14,6 @@ jest.mock('@react-navigation/native', () => {
   return { ...actual, useNavigation: () => ({ goBack: mockGoBack }) };
 });
 
-const fetchMock = global.fetch as jest.Mock;
-
 const fillForm = (
   getByLabelText: RenderResult['getByLabelText'],
   { username = 'grisen@example.test', password = 'hunter2' } = {},
@@ -36,29 +36,23 @@ it('renders the login form', () => {
 });
 
 it('logs in against the API and returns to the previous screen', async () => {
-  fetchMock.mockResolvedValueOnce({ ok: true, status: 200, json: async () => ({ token: 'token-123' }) });
+  const login = jest.spyOn(api, 'login').mockResolvedValue({ token: 'token-123' });
   const { getByText, getByLabelText } = renderWithProviders(<Login />);
 
   fillForm(getByLabelText);
   fireEvent.press(getByText('Logg inn'));
 
   await waitFor(() => expect(mockGoBack).toHaveBeenCalled());
-  expect(fetchMock).toHaveBeenCalledWith(
-    'https://dusken.example.test/auth/obtain-token/',
-    expect.objectContaining({
-      method: 'POST',
-      body: JSON.stringify({ username: 'grisen@example.test', password: 'hunter2' }),
-    }),
-  );
+  expect(login).toHaveBeenCalledWith('grisen@example.test', 'hunter2');
 });
 
 it('shows the server error when the credentials are rejected', async () => {
   jest.spyOn(console, 'log').mockImplementation(() => {});
-  fetchMock.mockResolvedValueOnce({
-    ok: false,
-    status: 400,
-    json: async () => ({ non_field_errors: ['Kan ikke logge inn med angitt brukernavn og passord'] }),
-  });
+  const invalidCredentials = new ApiError(
+    { non_field_errors: ['Kan ikke logge inn med angitt brukernavn og passord'] },
+    400,
+  );
+  jest.spyOn(api, 'login').mockRejectedValueOnce(invalidCredentials);
   const { getByText, getByLabelText, findByText } = renderWithProviders(<Login />);
 
   fillForm(getByLabelText);
@@ -70,7 +64,7 @@ it('shows the server error when the credentials are rejected', async () => {
 
 it('shows a generic message when the request fails on the network', async () => {
   jest.spyOn(console, 'log').mockImplementation(() => {});
-  fetchMock.mockRejectedValueOnce(new Error('network down'));
+  jest.spyOn(api, 'login').mockRejectedValueOnce(new Error('network down'));
   const { getByText, getByLabelText, findByText } = renderWithProviders(<Login />);
 
   fillForm(getByLabelText);
@@ -87,5 +81,5 @@ it('logs in a dev-fake user without hitting the network', async () => {
   fireEvent.press(getByText('Logg inn'));
 
   await waitFor(() => expect(mockGoBack).toHaveBeenCalled());
-  expect(fetchMock).not.toHaveBeenCalled();
+  expect(global.fetch).not.toHaveBeenCalled();
 });
diff --git a/src/modules/membership/Membership.test.tsx b/src/modules/membership/Membership.test.tsx
index 1570e11..7c04465 100644
--- a/src/modules/membership/Membership.test.tsx
+++ b/src/modules/membership/Membership.test.tsx
@@ -2,8 +2,10 @@ import { fireEvent } from '@testing-library/react-native';
 import React from 'react';
 import { RefreshControl } from 'react-native';
 
+import * as api from '@/api';
+import { ApiError } from '@/errors';
 import Membership from '@/modules/membership/Membership';
-import { mockMembershipTypesOnce, renderWithProviders, testUser } from '@/testUtils';
+import { renderWithProviders, testUser } from '@/testUtils';
 import type { UserType } from '@/types/data';
 
 const mockNavigate = jest.fn();
@@ -12,6 +14,10 @@ jest.mock('@react-navigation/native', () => ({
   useNavigation: () => ({ navigate: mockNavigate }),
 }));
 
+beforeEach(() => {
+  jest.clearAllMocks();
+});
+
 it('shows the membership pitch when logged out', async () => {
   const { findByText } = renderWithProviders(<Membership />);
 
@@ -22,7 +28,6 @@ it('shows the membership pitch when logged out', async () => {
 it('lets a logged in non-member pick a membership type and shows its price', async () => {
   const nonMember: UserType = { ...testUser, is_member: false, last_membership: null };
 
-  mockMembershipTypesOnce();
   const { findByText, getByText } = renderWithProviders(<Membership />, {
     initialToken: 'test-token',
     initialUser: nonMember,
@@ -46,7 +51,6 @@ it('lets a logged in non-member pick a membership type and shows its price', asy
 });
 
 it('shows the membership proof when logged in', async () => {
-  mockMembershipTypesOnce();
   const { findByText } = renderWithProviders(<Membership />, {
     initialToken: 'test-token',
     initialUser: testUser,
@@ -57,13 +61,7 @@ it('shows the membership proof when logged in', async () => {
 });
 
 it('fetches the user with the stored token when only the token survives a cold start', async () => {
-  // The user fetch resolves first; Proof then mounts and fetches membership types
-  (global.fetch as jest.Mock).mockResolvedValueOnce({
-    ok: true,
-    status: 200,
-    json: async () => testUser,
-  });
-  mockMembershipTypesOnce();
+  const fetchUserData = jest.spyOn(api, 'fetchUserData').mockResolvedValue(testUser);
 
   const { findByText } = renderWithProviders(<Membership />, {
     initialToken: 'test-token',
@@ -71,20 +69,12 @@ it('fetches the user with the stored token when only the token survives a cold s
 
   expect(await findByText('MEDLEM')).toBeTruthy();
   expect(await findByText('Test Testesen')).toBeTruthy();
-  expect(global.fetch).toHaveBeenCalledWith(
-    'https://dusken.example.test/api/me/',
-    expect.objectContaining({
-      method: 'GET',
-      headers: expect.objectContaining({ Authorization: 'Token test-token' }),
-    }),
-  );
+  expect(fetchUserData).toHaveBeenCalledWith('test-token');
 });
 
 it('refetches and renders updated user data on pull-to-refresh', async () => {
-  const fetchMock = global.fetch as jest.Mock;
   const nonMember: UserType = { ...testUser, is_member: false, last_membership: null };
 
-  mockMembershipTypesOnce();
   const { findByText, UNSAFE_getByType } = renderWithProviders(<Membership />, {
     initialToken: 'test-token',
     initialUser: nonMember,
@@ -92,25 +82,15 @@ it('refetches and renders updated user data on pull-to-refresh', async () => {
   expect(await findByText('Velg medlemskapstype')).toBeTruthy();
 
   // the server now reports an active membership, bought elsewhere
-  fetchMock.mockResolvedValueOnce({ ok: true, status: 200, json: async () => testUser });
+  const fetchUserData = jest.spyOn(api, 'fetchUserData').mockResolvedValue(testUser);
   fireEvent(UNSAFE_getByType(RefreshControl), 'refresh');
 
   expect(await findByText('MEDLEM')).toBeTruthy();
-  expect(fetchMock).toHaveBeenLastCalledWith(
-    'https://dusken.example.test/api/me/',
-    expect.objectContaining({
-      method: 'GET',
-      headers: expect.objectContaining({ Authorization: 'Token test-token' }),
-    }),
-  );
+  expect(fetchUserData).toHaveBeenCalledWith('test-token');
 });
 
 it('signs out when the stored token has been revoked', async () => {
-  (global.fetch as jest.Mock).mockResolvedValueOnce({
-    ok: false,
-    status: 401,
-    json: async () => ({ detail: 'Ugyldig token.' }),
-  });
+  jest.spyOn(api, 'fetchUserData').mockRejectedValueOnce(new ApiError({ detail: 'Ugyldig token.' }, 401));
 
   const { findByText } = renderWithProviders(<Membership />, {
     initialToken: 'revoked-token',
@@ -120,7 +100,6 @@ it('signs out when the stored token has been revoked', async () => {
 });
 
 it('logs out and shows the logged-out membership screen again', async () => {
-  mockMembershipTypesOnce();
   const { findByText } = renderWithProviders(<Membership />, {
     initialToken: 'test-token',
     initialUser: testUser,
diff --git a/src/modules/membership/Proof.test.tsx b/src/modules/membership/Proof.test.tsx
index c714bcc..738570c 100644
--- a/src/modules/membership/Proof.test.tsx
+++ b/src/modules/membership/Proof.test.tsx
@@ -2,9 +2,10 @@ import { fireEvent, waitFor } from '@testing-library/react-native';
 import * as Notifications from 'expo-notifications';
 import React from 'react';
 
+import * as api from '@/api';
 import Proof from '@/modules/membership/Proof';
-import { mockMembershipTypesOnce, renderWithProviders, testUser } from '@/testUtils';
-import type { UserType } from '@/types/data';
+import { renderWithProviders, testMembershipTypes, testUser } from '@/testUtils';
+import type { MembershipTypeOption, UserType } from '@/types/data';
 
 // The setup-wide stripe mock resolves initPaymentSheet/presentPaymentSheet
 // with { error: null }; useStripe() hands out these same jest.fn instances.
@@ -13,14 +14,10 @@ const { initPaymentSheet, presentPaymentSheet } = jest.requireMock('@stripe/stri
   presentPaymentSheet: jest.Mock;
 };
 
-const fetchMock = global.fetch as jest.Mock;
-
-const mockPaymentSheetResponse = () =>
-  fetchMock.mockResolvedValueOnce({
-    ok: true,
-    status: 200,
-    json: async () => ({ paymentIntent: 'pi_secret', ephemeralKey: 'ek_secret', customer: 'cus_123' }),
-  });
+const mockPaymentSheet = () =>
+  jest
+    .spyOn(api, 'requestStripePaymentSheet')
+    .mockResolvedValue({ paymentIntent: 'pi_secret', ephemeralKey: 'ek_secret', customer: 'cus_123' });
 
 const nonMember: UserType = { ...testUser, is_member: false, last_membership: null };
 
@@ -30,18 +27,19 @@ const expiredMember: UserType = {
   last_membership: { membership_type: 'standard', end_date: '2020-01-01' },
 };
 
-// The membership type query fires on mount, so its response must be queued
-// before render; later mockResolvedValueOnce calls queue up behind it.
-const renderProof = ({ user = nonMember, fetchUser = jest.fn() }: { user?: UserType; fetchUser?: () => void } = {}) => {
-  mockMembershipTypesOnce();
-  return renderWithProviders(
+const renderProof = ({
+  user = nonMember,
+  fetchUser = jest.fn(),
+  membershipTypes,
+}: { user?: UserType; fetchUser?: () => void; membershipTypes?: MembershipTypeOption[] | null } = {}) =>
+  renderWithProviders(
     <Proof onLogoutPress={jest.fn()} fetchUser={fetchUser} isRefetching={false} onDeletePress={jest.fn()} />,
     {
       initialToken: 'test-token',
       initialUser: user,
+      initialMembershipTypes: membershipTypes,
     },
   );
-};
 
 beforeEach(() => {
   jest.clearAllMocks();
@@ -49,7 +47,8 @@ beforeEach(() => {
 });
 
 it('disables the purchase button without showing a price while membership types load', async () => {
-  const { getByRole, findByText } = renderProof();
+  jest.spyOn(api, 'fetchMembershipTypes').mockResolvedValue(testMembershipTypes);
+  const { getByRole, findByText } = renderProof({ membershipTypes: null });
 
   // The label carries no amount until the query resolves
   expect(getByRole('button', { name: 'Kjøp medlemskap' })).toBeDisabled();
@@ -59,35 +58,31 @@ it('disables the purchase button without showing a price while membership types
 });
 
 it('shows an error with retry instead of a price when membership types fail to load', async () => {
-  fetchMock.mockRejectedValueOnce(new Error('network down'));
-  const { findByText, getByText, getByRole } = renderProof();
+  jest
+    .spyOn(api, 'fetchMembershipTypes')
+    .mockRejectedValueOnce(new Error('network down'))
+    .mockResolvedValue(testMembershipTypes);
+  const { findByText, getByText, getByRole } = renderProof({ membershipTypes: null });
 
   expect(await findByText('Kunne ikke hente priser')).toBeTruthy();
   expect(getByRole('button', { name: 'Kjøp medlemskap' })).toBeDisabled();
 
-  // Retrying consumes the queued successful mock and recovers the real price
+  // Retrying hits the recovered API and gets the real price
   fireEvent.press(getByText('Prøv igjen'));
   expect(await findByText('Kjøp medlemskap (300 NOK)')).toBeTruthy();
   expect(getByRole('button', { name: 'Kjøp medlemskap (300 NOK)' })).toBeEnabled();
 });
 
 it('purchases the preselected membership through the stripe payment sheet', async () => {
+  const requestPaymentSheet = mockPaymentSheet();
   const { findByText } = renderProof();
-  mockPaymentSheetResponse();
 
   // 'Ordinær' (slug: regular) is preselected; the button enables once the
   // membership type query has resolved and its price is shown
   fireEvent.press(await findByText('Kjøp medlemskap (300 NOK)'));
 
   expect(await findByText('Your order is confirmed!')).toBeTruthy();
-  expect(fetchMock).toHaveBeenCalledWith(
-    'https://dusken.example.test/api/stripe/payment-sheet/',
-    expect.objectContaining({
-      method: 'POST',
-      body: JSON.stringify({ membership_type: 'regular' }),
-      headers: expect.objectContaining({ Authorization: 'Token test-token' }),
-    }),
-  );
+  expect(requestPaymentSheet).toHaveBeenCalledWith('test-token', 'regular');
   expect(initPaymentSheet).toHaveBeenCalledWith(
     expect.objectContaining({
       paymentIntentClientSecret: 'pi_secret',
@@ -103,25 +98,22 @@ it('purchases the preselected membership through the stripe payment sheet', asyn
 });
 
 it('purchases the selected membership type, not the default', async () => {
+  const requestPaymentSheet = mockPaymentSheet();
   const { findByText } = renderProof();
-  mockPaymentSheetResponse();
 
   fireEvent.press(await findByText('Student'));
   fireEvent.press(await findByText('Kjøp medlemskap (150 NOK)'));
 
   expect(await findByText('Your order is confirmed!')).toBeTruthy();
-  expect(fetchMock).toHaveBeenCalledWith(
-    'https://dusken.example.test/api/stripe/payment-sheet/',
-    expect.objectContaining({ body: JSON.stringify({ membership_type: 'student' }) }),
-  );
+  expect(requestPaymentSheet).toHaveBeenCalledWith('test-token', 'student');
 });
 
 it('shows the stripe error when the payment sheet is not completed', async () => {
+  mockPaymentSheet();
   presentPaymentSheet.mockResolvedValueOnce({
     error: { code: 'Canceled', message: 'The payment flow has been canceled' },
   });
   const { findByText, queryByText } = renderProof();
-  mockPaymentSheetResponse();
 
   fireEvent.press(await findByText('Kjøp medlemskap (300 NOK)'));
 
@@ -131,12 +123,8 @@ it('shows the stripe error when the payment sheet is not completed', async () =>
 
 it('shows an error and does not present the sheet when the backend rejects the purchase', async () => {
   jest.spyOn(console, 'error').mockImplementation(() => {});
+  jest.spyOn(api, 'requestStripePaymentSheet').mockRejectedValueOnce(new Error('Ugyldig medlemskapstype'));
   const { findByText, getByRole } = renderProof();
-  fetchMock.mockResolvedValueOnce({
-    ok: false,
-    status: 400,
-    json: async () => ({ detail: 'Ugyldig medlemskapstype' }),
-  });
 
   fireEvent.press(await findByText('Kjøp medlemskap (300 NOK)'));
 
@@ -149,9 +137,9 @@ it('shows an error and does not present the sheet when the backend rejects the p
 
 it('shows an error and does not present the sheet when stripe fails to initialise it', async () => {
   jest.spyOn(console, 'error').mockImplementation(() => {});
+  mockPaymentSheet();
   initPaymentSheet.mockResolvedValueOnce({ error: { code: 'Failed', message: 'Invalid client secret' } });
   const { findByText } = renderProof();
-  mockPaymentSheetResponse();
 
   fireEvent.press(await findByText('Kjøp medlemskap (300 NOK)'));
 
diff --git a/src/modules/membership/UserDelete.test.tsx b/src/modules/membership/UserDelete.test.tsx
index e33f4d3..97b64e2 100644
--- a/src/modules/membership/UserDelete.test.tsx
+++ b/src/modules/membership/UserDelete.test.tsx
@@ -1,6 +1,8 @@
 import { fireEvent, waitFor } from '@testing-library/react-native';
 import React from 'react';
 
+import * as api from '@/api';
+import { ApiError } from '@/errors';
 import UserDelete from '@/modules/membership/UserDelete';
 import { renderWithProviders, testUser } from '@/testUtils';
 
@@ -10,8 +12,6 @@ jest.mock('@react-navigation/native', () => ({
   useNavigation: () => ({ navigate: mockNavigate, goBack: jest.fn() }),
 }));
 
-const fetchMock = global.fetch as jest.Mock;
-
 beforeEach(() => {
   jest.clearAllMocks();
 });
@@ -34,7 +34,7 @@ it('renders nothing and navigates back to Membership when not logged in', () =>
 });
 
 it('deletes the account and returns to Membership once the username is typed to confirm', async () => {
-  fetchMock.mockResolvedValueOnce({ ok: true, status: 204, json: async () => ({}) });
+  const deleteUser = jest.spyOn(api, 'deleteUser').mockResolvedValueOnce(undefined);
   const { getByText, getByDisplayValue } = renderWithProviders(<UserDelete />, {
     initialToken: 'test-token',
     initialUser: testUser,
@@ -44,21 +44,13 @@ it('deletes the account and returns to Membership once the username is typed to
   fireEvent.press(getByText('Jeg forstår, slett kontoen min'));
 
   await waitFor(() => expect(mockNavigate).toHaveBeenCalledWith('UserStack', { screen: 'Membership' }));
-  expect(fetchMock).toHaveBeenCalledWith(
-    'https://dusken.example.test/api/me/delete/',
-    expect.objectContaining({
-      method: 'DELETE',
-      headers: expect.objectContaining({ Authorization: 'Token test-token' }),
-    }),
-  );
+  expect(deleteUser).toHaveBeenCalledWith('test-token');
 });
 
 it('shows the server error when deletion fails', async () => {
-  fetchMock.mockResolvedValueOnce({
-    ok: false,
-    status: 400,
-    json: async () => ({ detail: 'Kunne ikke slette kontoen akkurat nå' }),
-  });
+  jest
+    .spyOn(api, 'deleteUser')
+    .mockRejectedValueOnce(new ApiError({ detail: 'Kunne ikke slette kontoen akkurat nå' }, 400));
   const { getByText, getByDisplayValue, findByText } = renderWithProviders(<UserDelete />, {
     initialToken: 'test-token',
     initialUser: testUser,
diff --git a/src/modules/register/UserRegister.test.tsx b/src/modules/register/UserRegister.test.tsx
index 4d2ec0b..05c71ea 100644
--- a/src/modules/register/UserRegister.test.tsx
+++ b/src/modules/register/UserRegister.test.tsx
@@ -2,8 +2,11 @@ import { act, fireEvent, waitFor, type RenderResult } from '@testing-library/rea
 import React from 'react';
 import { ActivityIndicator } from 'react-native';
 
+import * as api from '@/api';
+import { ApiError } from '@/errors';
 import UserRegister from '@/modules/register/UserRegister';
-import { renderWithProviders } from '@/testUtils';
+import { renderWithProviders, testUser } from '@/testUtils';
+import type { UserType } from '@/types/data';
 
 // The screen is pushed on top of Login and closes itself with goBack() once
 // registration succeeds; stub the navigation object so we can assert on that.
@@ -13,11 +16,6 @@ jest.mock('@react-navigation/native', () => {
   return { ...actual, useNavigation: () => ({ goBack: mockGoBack }) };
 });
 
-const fetchMock = global.fetch as jest.Mock;
-
-const mockResponseOnce = (json: unknown, ok = true) =>
-  fetchMock.mockResolvedValueOnce({ ok, status: ok ? 200 : 400, json: async () => json });
-
 const validFormValues: Record<string, string> = {
   Fornavn: 'Grisen',
   Etternavn: 'Testesen',
@@ -45,18 +43,21 @@ it('renders the registration form', () => {
 });
 
 it('disables the submit button while the form is incomplete', () => {
+  const registerUser = jest.spyOn(api, 'registerUser');
   const { getByText, getByRole, UNSAFE_queryByType } = renderWithProviders(<UserRegister />);
 
   expect(getByRole('button', { name: 'Registrer meg' })).toBeDisabled();
   fireEvent.press(getByText('Registrer meg'));
 
-  expect(fetchMock).not.toHaveBeenCalled();
+  expect(registerUser).not.toHaveBeenCalled();
   expect(UNSAFE_queryByType(ActivityIndicator)).toBeNull();
 });
 
 it('submits the form, shows a spinner while pending and navigates back on success', async () => {
-  let resolveRegister!: (response: { ok: boolean; status: number; json: () => Promise<unknown> }) => void;
-  fetchMock.mockImplementationOnce(() => new Promise((resolve) => (resolveRegister = resolve)));
+  let resolveRegister!: (result: { user: UserType; token: string }) => void;
+  const registerUser = jest
+    .spyOn(api, 'registerUser')
+    .mockImplementationOnce(() => new Promise((resolve) => (resolveRegister = resolve)));
   const { getByText, getByRole, getByLabelText, UNSAFE_getByType } = renderWithProviders(<UserRegister />);
 
   fillForm(getByLabelText);
@@ -65,34 +66,28 @@ it('submits the form, shows a spinner while pending and navigates back on succes
 
   // the spinner shows while the request is in flight
   await waitFor(() => expect(UNSAFE_getByType(ActivityIndicator)).toBeTruthy());
-  expect(fetchMock).toHaveBeenCalledWith(
-    'https://dusken.example.test/api/user/register/',
+  expect(registerUser).toHaveBeenCalledWith(
     expect.objectContaining({
-      method: 'POST',
-      body: JSON.stringify({
-        first_name: 'Grisen',
-        last_name: 'Testesen',
-        email: 'grisen@example.test',
-        phone_number: '+4712345678',
-        password: 'hunter2',
-      }),
+      first_name: 'Grisen',
+      last_name: 'Testesen',
+      email: 'grisen@example.test',
+      phone_number: '+4712345678',
+      password: 'hunter2',
     }),
   );
   expect(mockGoBack).not.toHaveBeenCalled();
 
   await act(async () => {
-    resolveRegister({
-      ok: true,
-      status: 200,
-      json: async () => ({ username: 'grisen', email: 'grisen@example.test', auth_token: 'token-456' }),
-    });
+    resolveRegister({ user: testUser, token: 'token-456' });
   });
 
   await waitFor(() => expect(mockGoBack).toHaveBeenCalled());
 });
 
 it('shows server field errors on the matching form field', async () => {
-  mockResponseOnce({ email: ['Denne e-postadressen er allerede i bruk'] }, false);
+  jest
+    .spyOn(api, 'registerUser')
+    .mockRejectedValueOnce(new ApiError({ email: ['Denne e-postadressen er allerede i bruk'] }, 400));
   const { getByText, getByRole, getByLabelText, findByText } = renderWithProviders(<UserRegister />);
 
   fillForm(getByLabelText);
@@ -103,7 +98,8 @@ it('shows server field errors on the matching form field', async () => {
   expect(mockGoBack).not.toHaveBeenCalled();
 });
 
-it('rejects an invalid e-mail address without hitting the network', async () => {
+it('rejects an invalid e-mail address without submitting', async () => {
+  const registerUser = jest.spyOn(api, 'registerUser');
   const { getByLabelText, findByText } = renderWithProviders(<UserRegister />);
 
   fillForm(getByLabelText, { 'E-post': 'not-an-email' });
@@ -111,5 +107,5 @@ it('rejects an invalid e-mail address without hitting the network', async () =>
   fireEvent(getByLabelText('Passord'), 'submitEditing');
 
   expect(await findByText('er ikke en gyldig e-post')).toBeTruthy();
-  expect(fetchMock).not.toHaveBeenCalled();
+  expect(registerUser).not.toHaveBeenCalled();
 });
diff --git a/src/testUtils.tsx b/src/testUtils.tsx
index 844de34..74dcb89 100644
--- a/src/testUtils.tsx
+++ b/src/testUtils.tsx
@@ -22,27 +22,21 @@ export const testUser: UserType = {
   },
 };
 
-/** The purchase options offered in the app, as served by /api/graphql/. */
+/** The purchase options offered in the app. */
 export const testMembershipTypes: MembershipTypeOption[] = [
   { slug: 'student', price: 15000 },
   { slug: 'regular', price: 30000 },
   { slug: 'support', price: 50000 },
 ];
 
-/** Queue a successful /api/graphql/ membership types response on the fetch mock. */
-export function mockMembershipTypesOnce(membershipTypes: MembershipTypeOption[] = testMembershipTypes) {
-  (global.fetch as jest.Mock).mockResolvedValueOnce({
-    ok: true,
-    status: 200,
-    json: async () => ({ data: { membershipTypes } }),
-  });
-}
-
 interface RenderWithProvidersOptions {
   /** Auth token the app has stored; being set means the user is logged in. */
   initialToken?: string | null;
   /** Already-fetched user data, as after a completed /api/me/ request. */
   initialUser?: UserType | null;
+  /** Membership purchase options already in the cache; null leaves the query
+   * empty for tests that exercise its loading and error states. */
+  initialMembershipTypes?: MembershipTypeOption[] | null;
 }
 
 /**
@@ -51,7 +45,11 @@ interface RenderWithProvidersOptions {
  */
 export function renderWithProviders(
   ui: ReactElement,
-  { initialToken = null, initialUser = null }: RenderWithProvidersOptions = {},
+  {
+    initialToken = null,
+    initialUser = null,
+    initialMembershipTypes = testMembershipTypes,
+  }: RenderWithProvidersOptions = {},
 ) {
   const queryClient = new QueryClient({
     defaultOptions: {
@@ -64,6 +62,9 @@ export function renderWithProviders(
   if (initialUser) {
     queryClient.setQueryData(queryKeys.user, initialUser);
   }
+  if (initialMembershipTypes) {
+    queryClient.setQueryData(queryKeys.membershipTypes, initialMembershipTypes);
+  }
 
   const result = render(
     <QueryClientProvider client={queryClient}>