Improve error reporing on assert receive

lib/blank_assertions.ex

@@ -39,7 +39,7 @@ defmodule BlankAssertions do
           100 -> {:messages, messages} = Process.info(self(), :messages)
                 mailbox = Enum.map_join(messages, ", ", &inspect/1)
                 message = inspect(unquote(expr))
-                ExUnit.Assertions.flunk("message #{message} not found in [#{mailbox}]")
+                ExUnit.Assertions.flunk("Message #{message} not found in process mailbox. Mailbox contains: [#{mailbox}]")
         end
       end
     end

lib/display.ex

@@ -45,7 +45,10 @@ defmodule Display do
   end
 
   defp format_failure(%{error: %ExUnit.AssertionError{expr: @no_value, message: message}, file: file, line: line}) do
-    format_assertion_error(message, file, line)
+    """
+    #{format_cyan("Assertion failed in #{file}:#{line}")}
+    #{format_red(message)}
+    """
   end
 
   defp format_failure(%{error: %ExUnit.AssertionError{expr: expr}, file: file, line: line}) do