added test for bad TLD, better named 404 url test

spec/create_spec.rb

@@ -66,7 +66,7 @@ describe "Submit API request to create new link" do
     expect(response_json['message']).to eq('invalid url parameter')
   end
 
-  it "should return with a 400 status and 'url not found' message when an invalid url is submitted" do
+  it "should return with a 400 status and 'url not found' message when a 404 url is submitted" do
     data = {
       url: 'http://google.com/example'
     }
@@ -75,4 +75,14 @@ describe "Submit API request to create new link" do
     response_json = JSON.parse(last_response.body)
     expect(response_json['message']).to eq('url not found')
   end
+
+  it "should return with a 400 status and 'url not found' message when a URL with no DNS is submitted" do
+    data = {
+      url: 'http://bad.tld'
+    }
+    post('/links', data.to_json, "CONTENT_TYPE" => "application/json")
+    expect(last_response.status).to eq(400)
+    response_json = JSON.parse(last_response.body)
+    expect(response_json['message']).to eq('url does not resolve')
+  end
 end