[remix] Add unit tests (#9469)

Moves parts of the `@vercel/remix` builder into util functions that have isolated unit tests. No functionality changes.

packages/remix/test/unit.get-regexp-from-path.test.ts

@@ -0,0 +1,124 @@
+import { getRegExpFromPath } from '../src/utils';
+
+describe('getRegExpFromPath()', () => {
+  describe('paths without parameters', () => {
+    it.each([{ path: 'index' }, { path: 'api/hello' }, { path: 'projects' }])(
+      'should return `false` for "$path"',
+      ({ path }) => {
+        expect(getRegExpFromPath(path)).toEqual(false);
+      }
+    );
+  });
+
+  describe.each([
+    {
+      path: '*',
+      urls: [
+        {
+          url: '/',
+          expected: false,
+        },
+        {
+          url: '/foo',
+          expected: true,
+        },
+        {
+          url: '/projects/foo',
+          expected: true,
+        },
+        {
+          url: '/projects/another',
+          expected: true,
+        },
+        {
+          url: '/to/infinity/and/beyond',
+          expected: true,
+        },
+      ],
+    },
+    {
+      path: 'projects/*',
+      urls: [
+        {
+          url: '/',
+          expected: false,
+        },
+        {
+          url: '/foo',
+          expected: false,
+        },
+        {
+          url: '/projects/foo',
+          expected: true,
+        },
+        {
+          url: '/projects/another',
+          expected: true,
+        },
+      ],
+    },
+    {
+      path: ':foo',
+      urls: [
+        {
+          url: '/',
+          expected: false,
+        },
+        {
+          url: '/foo',
+          expected: true,
+        },
+        {
+          url: '/projects/foo',
+          expected: false,
+        },
+        {
+          url: '/projects/another',
+          expected: false,
+        },
+      ],
+    },
+    {
+      path: 'blog/:id/edit',
+      urls: [
+        {
+          url: '/',
+          expected: false,
+        },
+        {
+          url: '/foo',
+          expected: false,
+        },
+        {
+          url: '/blog/123/edit',
+          expected: true,
+        },
+        {
+          url: '/blog/456/edit',
+          expected: true,
+        },
+        {
+          url: '/blog/123/456/edit',
+          expected: false,
+        },
+        {
+          url: '/blog/123/another',
+          expected: false,
+        },
+      ],
+    },
+  ])('with path "$path"', ({ path, urls }) => {
+    const re = getRegExpFromPath(path) as RegExp;
+
+    it('should return RegExp', () => {
+      expect(re).toBeInstanceOf(RegExp);
+    });
+
+    it.each(urls)(
+      'should match URL "$url" - $expected',
+      ({ url, expected }) => {
+        expect(re.test(url)).toEqual(expected);
+      }
+    );
+  });
+});