chore: Remove pattern in favour of definePattern

packages/snaps-controllers/src/snaps/SnapController.test.tsx

@@ -6597,7 +6597,7 @@ describe('SnapController', () => {
           [snapId]: {},
         }),
       ).rejects.toThrow(
-        `Invalid snap ID: Expected the value to satisfy a union of \`intersection | string\`, but received: "foo".`,
+        `Invalid snap ID: Invalid or no prefix found. Expected Snap ID to start with one of: "npm:", "local:", but received: "foo".`,
       );
 
       controller.destroy();

packages/snaps-utils/coverage.json

@@ -1,6 +1,6 @@
 {
   "branches": 99.74,
-  "functions": 98.92,
+  "functions": 98.93,
   "lines": 99.61,
-  "statements": 96.91
+  "statements": 96.94
 }

packages/snaps-utils/src/snaps.test.ts

@@ -14,6 +14,7 @@ import {
   verifyRequestedSnapPermissions,
   stripSnapPrefix,
   isSnapId,
+  SnapIdPrefixStruct,
 } from './snaps';
 import { MOCK_SNAP_ID } from './test-utils';
 import { uri, WALLET_SNAP_PERMISSION_KEY } from './types';
@@ -52,14 +53,14 @@ describe('assertIsValidSnapId', () => {
         // TODO: Either fix this lint violation or explain why it's necessary to
         //  ignore.
         // eslint-disable-next-line @typescript-eslint/restrict-template-expressions, @typescript-eslint/no-base-to-string
-        `Invalid snap ID: Expected the value to satisfy a union of \`intersection | string\`, but received: ${value}.`,
+        `Invalid snap ID: Expected a string, but received: ${value}.`,
       );
     },
   );
 
   it('throws for invalid snap id', () => {
     expect(() => assertIsValidSnapId('foo:bar')).toThrow(
-      `Invalid snap ID: Expected the value to satisfy a union of \`intersection | string\`, but received: "foo:bar".`,
+      `Invalid snap ID: Invalid or no prefix found. Expected Snap ID to start with one of: "npm:", "local:", but received: "foo:bar".`,
     );
   });
 
@@ -75,22 +76,27 @@ describe('assertIsValidSnapId', () => {
     ).not.toThrow();
   });
 
+  it('disallows whitespace at the beginning', () => {
+    expect(() => assertIsValidSnapId(' local:http://localhost:8000')).toThrow(
+      'Invalid snap ID: Invalid or no prefix found. Expected Snap ID to start with one of: "npm:", "local:", but received: " local:http://localhost:8000".',
+    );
+  });
+
   it.each([
-    ' local:http://localhost:8000',
     'local:http://localhost:8000 ',
     'local:http://localhost:8000\n',
     'local:http://localhost:8000\r',
   ])('disallows whitespace #%#', (value) => {
     expect(() => assertIsValidSnapId(value)).toThrow(
-      /Invalid snap ID: Expected the value to satisfy a union of `intersection \| string`, but received: .+\./u,
+      /Invalid snap ID: Expected a value of type `Base Snap Id`, but received: .+\./u,
     );
   });
 
   it.each(['local:😎', 'local:␡'])(
     'disallows non-ASCII symbols #%#',
     (value) => {
       expect(() => assertIsValidSnapId(value)).toThrow(
-        `Invalid snap ID: Expected the value to satisfy a union of \`intersection | string\`, but received: "${value}".`,
+        `Invalid snap ID: Expected a value of type \`Base Snap Id\`, but received: \`"${value}"\`.`,
       );
     },
   );
@@ -238,6 +244,36 @@ describe('HttpSnapIdStruct', () => {
   });
 });
 
+describe('SnapIdPrefixStruct', () => {
+  it.each(['local:', 'npm:', 'local:foobar', 'npm:foobar'])(
+    'validates "%s" as proper Snap ID prefix',
+    (value) => {
+      expect(is(value, SnapIdPrefixStruct)).toBe(true);
+    },
+  );
+
+  it.each([
+    0,
+    1,
+    false,
+    true,
+    {},
+    [],
+    uri,
+    URL,
+    new URL('http://github.com'),
+    '',
+    'local',
+    'npm',
+    'foo:npm',
+    'foo:local',
+    'localfoobar',
+    'npmfoobar',
+  ])('invalidates an improper Snap ID prefix', (value) => {
+    expect(is(value, SnapIdPrefixStruct)).toBe(false);
+  });
+});
+
 describe('isSnapPermitted', () => {
   it("will check an origin's permissions object to see if it has permission to interact with a specific snap", () => {
     const validPermissions: SubjectPermissions<PermissionConstraint> = {

packages/snaps-utils/src/snaps.ts

@@ -4,22 +4,24 @@ import type {
   PermissionConstraint,
 } from '@metamask/permission-controller';
 import type { BlockReason } from '@metamask/snaps-registry';
-import type { SnapId, Snap as TruncatedSnap } from '@metamask/snaps-sdk';
+import {
+  selectiveUnion,
+  type SnapId,
+  type Snap as TruncatedSnap,
+} from '@metamask/snaps-sdk';
 import type { Struct } from '@metamask/superstruct';
 import {
   is,
   empty,
   enums,
   intersection,
   literal,
-  pattern,
   refine,
   string,
-  union,
   validate,
 } from '@metamask/superstruct';
 import type { Json } from '@metamask/utils';
-import { assert, isObject, assertStruct } from '@metamask/utils';
+import { assert, isObject, assertStruct, definePattern } from '@metamask/utils';
 import { base64 } from '@scure/base';
 import stableStringify from 'fast-json-stable-stringify';
 import validateNPMPackage from 'validate-npm-package-name';
@@ -228,7 +230,10 @@ export async function validateSnapShasum(
 export const LOCALHOST_HOSTNAMES = ['localhost', '127.0.0.1', '[::1]'] as const;
 
 // Require snap ids to only consist of printable ASCII characters
-export const BaseSnapIdStruct = pattern(string(), /^[\x21-\x7E]*$/u);
+export const BaseSnapIdStruct = definePattern(
+  'Base Snap Id',
+  /^[\x21-\x7E]*$/u,
+);
 
 const LocalSnapIdSubUrlStruct = uri({
   protocol: enums(['http:', 'https:']),
@@ -284,7 +289,35 @@ export const HttpSnapIdStruct = intersection([
   }),
 ]) as unknown as Struct<string, null>;
 
-export const SnapIdStruct = union([NpmSnapIdStruct, LocalSnapIdStruct]);
+export const SnapIdPrefixStruct = refine(
+  string(),
+  'Snap ID prefix',
+  (value) => {
+    if (
+      Object.values(SnapIdPrefixes).some((prefix) => value.startsWith(prefix))
+    ) {
+      return true;
+    }
+
+    const allowedPrefixes = Object.values(SnapIdPrefixes)
+      .map((prefix) => `"${prefix}"`)
+      .join(', ');
+
+    return `Invalid or no prefix found. Expected Snap ID to start with one of: ${allowedPrefixes}, but received: "${value}"`;
+  },
+);
+
+export const SnapIdStruct = selectiveUnion((value) => {
+  if (typeof value === 'string' && value.startsWith(SnapIdPrefixes.npm)) {
+    return NpmSnapIdStruct;
+  }
+
+  if (typeof value === 'string' && value.startsWith(SnapIdPrefixes.local)) {
+    return LocalSnapIdStruct;
+  }
+
+  return SnapIdPrefixStruct;
+});
 
 /**
  * Extracts the snap prefix from a snap ID.

packages/snaps-utils/src/types.ts

@@ -2,7 +2,6 @@ import {
   instance,
   is,
   optional,
-  pattern,
   refine,
   size,
   string,
@@ -12,7 +11,7 @@ import {
 } from '@metamask/superstruct';
 import type { Infer, Struct } from '@metamask/superstruct';
 import type { Json } from '@metamask/utils';
-import { VersionStruct } from '@metamask/utils';
+import { definePattern, VersionStruct } from '@metamask/utils';
 
 import type { SnapCaveatType } from './caveats';
 import type { SnapFunctionExports, SnapRpcHookArgs } from './handlers';
@@ -26,8 +25,8 @@ export enum NpmSnapFileNames {
 }
 
 export const NameStruct = size(
-  pattern(
-    string(),
+  definePattern(
+    'Snap Name',
     /^(?:@[a-z0-9-*~][a-z0-9-*._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$/u,
   ),
   1,