use selectiveUnion

Author: GuillaumeRx

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

@@ -52,14 +52,14 @@ 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 | Base Snap Id\`, 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 | Base Snap Id\`, but received: "foo:bar".`,
+      `Invalid snap ID: Invalid or no prefix found for "foo:bar".`,
     );
   });
 
@@ -75,22 +75,27 @@ 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 for " 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 \| Base Snap Id`, 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 | Base Snap Id\`, but received: "${value}".`,
+        `"Invalid snap ID: Expected a value of type \`Base Snap Id\`, but received: "${value}".`,
       );
     },
   );

packages/snaps-utils/src/snaps.ts

@@ -4,7 +4,11 @@ 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,
@@ -14,7 +18,6 @@ import {
   literal,
   refine,
   string,
-  union,
   validate,
 } from '@metamask/superstruct';
 import type { Json } from '@metamask/utils';
@@ -286,7 +289,31 @@ export const HttpSnapIdStruct = intersection([
   }),
 ]) as unknown as Struct<string, null>;
 
-export const SnapIdStruct = union([NpmSnapIdStruct, LocalSnapIdStruct]);
+export const SnapIdPrefixStruct = refine(
+  string(),
+  'Valid Prefix Snap Id',
+  (value) => {
+    if (
+      Object.values(SnapIdPrefixes).some((prefix) => value.startsWith(prefix))
+    ) {
+      return true;
+    }
+
+    return `Invalid or no prefix found for "${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.