Fix mock set resolution for folder-based organization

lib/mock.js

@@ -6,7 +6,7 @@ import {pathToRegexp} from 'path-to-regexp';
 
 const methodRegExp = /^([a-z+]+?)_/i;
 const paramsRegExp = /[$?]([^.\s]+$)/;
-const setRegExp = /__([\w-]+?)$/;
+const setRegExp = /__([a-z\d][\w-]*)$/i;
 const defaultType = 'application/octet-stream';
 
 const importFresh = async (moduleName) => {
@@ -65,7 +65,7 @@ export function getMock(basePath, file, data = undefined) {
 
   const dirComponents = path
     .dirname(file)
-    .split(path.delimiter)
+    .split(path.sep)
     .filter((c) => c && c !== '.');
   const fileComponents = basename.split('#').filter(Boolean);
   let methods = null;

test/mocks/users/get_.json

@@ -0,0 +1 @@
+{"username": "default", "role": "guest"}

test/mocks/users/get___admin.json

@@ -0,0 +1 @@
+{"username": "admin", "role": "admin"}

test/mocks/users/get___user.json

@@ -0,0 +1 @@
+{"username": "john", "role": "user"}

test/smoke.spec.js

@@ -119,6 +119,26 @@ describe('smoke server', () => {
 
       expect(response.body).toEqual({hello: 'world'});
     });
+
+    it('should use mock set with folder structure (admin set)', async () => {
+      app = await createServer({...options, set: 'admin'});
+      const response = await request(app).get('/users');
+
+      expect(response.body).toEqual({username: 'admin', role: 'admin'});
+    });
+
+    it('should use mock set with folder structure (user set)', async () => {
+      app = await createServer({...options, set: 'user'});
+      const response = await request(app).get('/users');
+
+      expect(response.body).toEqual({username: 'john', role: 'user'});
+    });
+
+    it('should use default mock when no set is specified with folder structure', async () => {
+      const response = await request(app).get('/users');
+
+      expect(response.body).toEqual({username: 'default', role: 'guest'});
+    });
   });
 
   describe('should handle custom responses', () => {