fix: do not fetch payment methods until a user has selected a token

packages/ramps-controller/CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- `setSelectedProvider` no longer fetches payment methods when no token is selected ([#8342](https://github.com/MetaMask/core/pull/8342))
+  - Previously, the `tokenSupportedByProvider` guard evaluated to `true` when no token was selected (vacuous truth), causing an unfiltered payment methods fetch with an empty `crypto` parameter. The guard now requires a token to be selected before triggering the fetch.
+
 ## [12.1.0]
 
 ### Added

packages/ramps-controller/src/RampsController.test.ts

@@ -2869,11 +2869,21 @@ describe('RampsController', () => {
       );
     });
 
-    it('fetches getPaymentMethods when provider has no supportedCryptoCurrencies field', async () => {
+    it('fetches getPaymentMethods when provider has no supportedCryptoCurrencies field and a token is selected', async () => {
       const providerWithoutField: Provider = { ...mockProvider };
       delete (providerWithoutField as Partial<Provider>)
         .supportedCryptoCurrencies;
 
+      const selectedToken: RampsToken = {
+        assetId: 'eip155:1/slip44:60',
+        chainId: 'eip155:1',
+        name: 'Ether',
+        symbol: 'ETH',
+        decimals: 18,
+        iconUrl: '',
+        tokenSupported: true,
+      };
+
       const getPaymentMethodsMock = jest.fn(async () => ({ payments: [] }));
 
       await withController(
@@ -2882,6 +2892,7 @@ describe('RampsController', () => {
             state: {
               userRegion: createMockUserRegion('us-ca'),
               providers: createResourceState([providerWithoutField], null),
+              tokens: createResourceState(null, selectedToken),
             },
           },
         },
@@ -2903,6 +2914,36 @@ describe('RampsController', () => {
       );
     });
 
+    it('skips getPaymentMethods when no token is selected', async () => {
+      const getPaymentMethodsMock = jest.fn(async () => ({ payments: [] }));
+
+      await withController(
+        {
+          options: {
+            state: {
+              userRegion: createMockUserRegion('us-ca'),
+              providers: createResourceState([mockProvider], null),
+            },
+          },
+        },
+        async ({ rootMessenger }) => {
+          rootMessenger.registerActionHandler(
+            'RampsService:getPaymentMethods',
+            getPaymentMethodsMock,
+          );
+
+          rootMessenger.call(
+            'RampsController:setSelectedProvider',
+            mockProvider.id,
+          );
+
+          await new Promise((resolve) => setTimeout(resolve, 0));
+
+          expect(getPaymentMethodsMock).not.toHaveBeenCalled();
+        },
+      );
+    });
+
     it('fetches getPaymentMethods when selected token is explicitly supported by the new provider', async () => {
       const supportedToken: RampsToken = {
         assetId: 'eip155:1/slip44:60',
@@ -4417,6 +4458,16 @@ describe('RampsController', () => {
     });
 
     it('does not update paymentMethods when selectedProvider changes during request', async () => {
+      const selectedToken: RampsToken = {
+        assetId: 'eip155:1/slip44:60',
+        chainId: 'eip155:1',
+        name: 'Ether',
+        symbol: 'ETH',
+        decimals: 18,
+        iconUrl: '',
+        tokenSupported: true,
+      };
+
       const providerA: Provider = {
         id: '/providers/provider-a',
         name: 'Provider A',
@@ -4472,7 +4523,7 @@ describe('RampsController', () => {
           options: {
             state: {
               userRegion: createMockUserRegion('us-ca'),
-              tokens: createResourceState(null, null),
+              tokens: createResourceState(null, selectedToken),
               providers: createResourceState([providerA, providerB], providerA),
               paymentMethods: createResourceState([], null),
             },

packages/ramps-controller/src/RampsController.ts

@@ -1228,22 +1228,21 @@ export class RampsController extends BaseController<
     const selectedToken = this.state.tokens.selected;
     const supportedCryptos = provider.supportedCryptoCurrencies;
 
-    // Only fetch payment methods if the selected token is supported by the new
-    // provider. If it isn't, the payment methods request would fail or return
-    // empty for the wrong reason; the UI will show the Token Not Available modal
-    // so the user can change token or pick a different provider.
+    // Only fetch payment methods when a token is selected AND that token is
+    // supported by the new provider. Without a token the API receives an empty
+    // `crypto` param and returns an unfiltered list — payment methods must
+    // always be scoped to a specific token.
     const assetId = selectedToken?.assetId;
-    const tokenSupportedByProvider = !(
-      assetId && supportedCryptos?.[assetId] === false
-    );
+    const shouldFetchPaymentMethods =
+      Boolean(assetId) && !(supportedCryptos?.[assetId as string] === false);
 
     this.update((state) => {
       state.providers.selected = provider;
       state.providerAutoSelected = options?.autoSelected ?? false;
       resetResource(state, 'paymentMethods');
     });
 
-    if (tokenSupportedByProvider) {
+    if (shouldFetchPaymentMethods) {
       this.#fireAndForget(
         this.getPaymentMethods(regionCode, { provider: provider.id }),
       );