Handle case where container field URL is empty string

lib/fmrest/v1/container_fields.rb

@@ -25,15 +25,19 @@ module ContainerFields
       def fetch_container_data(container_field_url, base_connection = nil)
         require "open-uri"
 
+        if container_field_url == ""
+          raise FmRest::ContainerFieldError, "Container field URL is empty string"
+        end
+
         begin
           url = URI(container_field_url)
-        rescue ::URI::InvalidURIError
+        rescue ::URI::InvalidURIError, ArgumentError
           raise FmRest::ContainerFieldError, "Invalid container field URL `#{container_field_url}'"
         end
 
         # Make sure we don't try to open anything on the file:/ URI scheme
         unless url.scheme.match(/\Ahttps?\Z/)
-          raise FmRest::ContainerFieldError, "Container URL is not HTTP (#{container_field_url})"
+          raise FmRest::ContainerFieldError, "Container field URL is not HTTP (#{container_field_url})"
         end
 
         ssl_options = base_connection && base_connection.ssl && base_connection.ssl.to_hash

spec/core/v1/container_fields_spec.rb

@@ -8,12 +8,20 @@
   describe "#fetch_container_data" do
     let(:container_url) { "https://foo.bar:4444/qux" }
 
+    context "when given an empty string" do
+      it { expect { extendee.fetch_container_data("") }.to raise_error(FmRest::ContainerFieldError, /Container field URL is empty string/) }
+    end
+
+    context "when given a nil URL" do
+      it { expect { extendee.fetch_container_data(nil) }.to raise_error(FmRest::ContainerFieldError, /Invalid container field URL/) }
+    end
+
     context "when given an invalid URL" do
       it { expect { extendee.fetch_container_data("boo boo") }.to raise_error(FmRest::ContainerFieldError, /Invalid container field URL/) }
     end
 
     context "when given a non-http URL" do
-      it { expect { extendee.fetch_container_data("file://foo/bar") }.to raise_error(FmRest::ContainerFieldError, /Container URL is not HTTP/) }
+      it { expect { extendee.fetch_container_data("file://foo/bar") }.to raise_error(FmRest::ContainerFieldError, /Container field URL is not HTTP/) }
     end
 
     context "when the given URL is not a redirect" do