fix: show a more helpful error when attempting to parse a URI that is…

… not a pact

Closes: pact-foundation/pact-provider-verifier#25

lib/pact/consumer_contract/consumer_contract.rb

@@ -14,6 +14,8 @@
 
 module Pact
 
+  class UnrecognizePactFormatError < ::Pact::Error; end
+
   class ConsumerContract
 
     include SymbolizeKeys
@@ -42,7 +44,7 @@ def self.from_hash(hash)
       parsers.each do | parser |
         return parser.call(hash) if parser.can_parse?(hash)
       end
-      raise Pact::Error.new("No consumer contract parser found for hash: #{hash}")
+      raise Pact::UnrecognizePactFormatError.new("This document does not use a recognised Pact format: #{hash}")
     end
 
     def self.from_json string
@@ -52,6 +54,8 @@ def self.from_json string
 
     def self.from_uri uri, options = {}
       from_json(Pact::PactFile.read(uri, options))
+    rescue UnrecognizePactFormatError
+      raise Pact::UnrecognizePactFormatError.new("This document does not use a recognised Pact format. Please check that #{uri} is a valid pact file.")
     end
 
     def self.maintain_backwards_compatiblity_with_producer_keys string

lib/pact/consumer_contract/pact_file.rb

@@ -40,7 +40,7 @@ def render_pact(uri_string, options)
     end
 
     private
-    
+
     def local? uri
       !uri.start_with?("http://", "https://")
     end
@@ -74,7 +74,7 @@ def get_remote_with_retry(uri_string, options)
         end
       end
     end
-    
+
     def get_remote(uri, options)
       request = Net::HTTP::Get.new(uri)
       request.basic_auth(options[:username], options[:password]) if options[:username]

spec/fixtures/not-a-pact.json

@@ -0,0 +1,3 @@
+{
+  "foo": "bar"
+}

spec/lib/pact/consumer_contract/consumer_contract_spec.rb

@@ -3,6 +3,26 @@
 
 module Pact
   describe ConsumerContract do
+    describe "from_uri" do
+      context "when the URL does not point to a valid pact" do
+        subject { ConsumerContract.from_uri('spec/fixtures/not-a-pact.json') }
+
+        it "raises a helpful error" do
+          expect { subject }.to raise_error UnrecognizePactFormatError, /Please check that spec/
+        end
+      end
+    end
+
+    describe "from_hash" do
+      context "when the hash is not a valid pact" do
+        subject { ConsumerContract.from_hash({'foo' => 'bar'}) }
+
+        it "raises a helpful error" do
+          expect { subject }.to raise_error UnrecognizePactFormatError, 'This document does not use a recognised Pact format: {"foo"=>"bar"}'
+        end
+      end
+    end
+
     describe ".from_json" do
 
       let(:loaded_pact) { ConsumerContract.from_json(string) }