test: add coverage for invalid URLs

tests/test_scope.js

@@ -47,6 +47,29 @@ describe('`Scope#constructor`', () => {
     expect(() => nock('localhost/foo')).to.throw()
     expect(() => nock('foo.com:1234')).to.throw()
   })
+
+  it('throws on invalid URL format', async () => {
+    expect(() => nock(['This is not a url'])).to.throw()
+    // The following contains all valid properties of WHATWG URL, but is not an 
+    // instance of URL. Maybe we should support object literals some day? A 
+    // simple duck-type validator would suffice.
+    expect(() =>
+      nock({
+        href: 'http://google.com/foo',
+        origin: 'http://google.com',
+        protocol: 'http:',
+        username: '',
+        password: '',
+        host: 'google.com',
+        hostname: 'google.com',
+        port: 80,
+        pathname: '/foo',
+        search: '',
+        searchParams: {},
+        hash: '',
+      })
+    ).to.throw()
+  })
 })
 
 describe('`Scope#remove()`', () => {