throws error when valid response is not found

lib/exvcr/exception.ex

@@ -1 +1,2 @@
-defexception ExVCRError, message: "error"
+defexception ExVCR.InvalidRequestError, message: "error"
+defexception ExVCR.FileNotFoundError, message: "error"

lib/exvcr/handler.ex

@@ -16,7 +16,7 @@ defmodule ExVCR.Handler do
   defp verify_response(response, recorder, target_url) do
     options = Options.get(recorder.options)
     if response == nil and options[:custom] == true do
-      raise ExVCRError.new(message: "response for \"#{target_url}\" was not found in the custom cassette")
+      raise ExVCR.InvalidRequestError.new(message: "response for \"#{target_url}\" was not found in the custom cassette")
     else
       response
     end

lib/exvcr/json.ex

@@ -17,9 +17,12 @@ defmodule ExVCR.JSON do
 
   def load(fixture, options) do
     file_name = get_file_path(fixture, options)
+    custom_option = options[:custom]
     case File.exists?(file_name) do
       true -> File.read!(file_name) |> JSEX.decode! |> Enum.map(&from_string/1)
-      _    -> []
+      false when custom_option ->
+        raise ExVCR.FileNotFoundError.new(message: "cassette file \"#{file_name}\" not found")
+      _ -> []
     end
   end
 

test/exvcr_test.exs

@@ -59,27 +59,35 @@ defmodule ExVCR.MockTest do
     end
   end
 
-  test "custom response with valid response file" do
+  test "custom with valid response" do
     use_cassette "response_mocking", custom: true do
       assert HTTPotion.get("http://example.com", []).body =~ %r/Custom Response/
     end
   end
 
-  test "custom response without valid response file" do
-    assert_raise ExVCRError, fn ->
+  test "custom response with regexp url" do
+    use_cassette "response_mocking_regex", custom: true do
+      HTTPotion.get("http://example.com/something/abc", []).body =~ %r/Custom Response/
+    end
+  end
+
+  test "custom without valid response throws error" do
+    assert_raise ExVCR.InvalidRequestError, fn ->
       use_cassette "response_mocking", custom: true do
         HTTPotion.get("http://example.com/invalid", [])
       end
     end
   end
 
-  test "custom response with regexp url" do
-    use_cassette "response_mocking_regex", custom: true do
-      HTTPotion.get("http://example.com/something/abc", []).body =~ %r/Custom Response/
+  test "custom without valid response file throws error" do
+    assert_raise ExVCR.FileNotFoundError, fn ->
+      use_cassette "invalid_file_response", custom: true do
+        HTTPotion.get("http://example.com", [])
+      end
     end
+    :meck.unload(:ibrowse)  # temporary fix
   end
 
-
   defp assert_response(response, function // nil) do
     assert response.success?(:extra)
     assert response.headers[:Connection] == "keep-alive"