Improve doctest failure messages for exception assertions (#4889)

lib/ex_unit/lib/ex_unit/assertions.ex

@@ -476,17 +476,19 @@ defmodule ExUnit.Assertions do
   def assert_raise(exception, message, function) when is_function(function) do
     error = assert_raise(exception, function)
 
-    is_match = cond do
+    match? = cond do
       is_binary(message) -> Exception.message(error) == message
       Regex.regex?(message) -> Exception.message(error) =~ message
     end
 
-    msg = "Wrong message for #{inspect exception}\n" <>
-          "Expected:\n" <>
-          "  #{inspect message}\n" <>
-          "Got:\n" <>
-          "  #{inspect Exception.message(error)}"
-    assert is_match, message: msg
+    message =
+      "Wrong message for #{inspect exception}\n" <>
+      "expected:\n" <>
+      "  #{inspect message}\n" <>
+      "actual:\n" <>
+      "  #{inspect Exception.message(error)}"
+
+    assert match?, message: message
 
     error
   end

lib/ex_unit/lib/ex_unit/doc_test.ex

@@ -330,25 +330,35 @@ defmodule ExUnit.DocTest do
 
     quote do
       stack = unquote(stack)
-      expr  = unquote(String.trim(expr))
-      spec  = inspect(unquote(exception)) <> " with message " <> inspect(unquote(message))
+      expr = unquote(String.trim(expr))
 
       try do
         unquote(expr_ast)
       rescue
         error ->
-          unless error.__struct__ == unquote(exception) and
-                 Exception.message(error) == unquote(message) do
-            got = inspect(error.__struct__) <> " with message " <> inspect(Exception.message(error))
-            reraise ExUnit.AssertionError,
-              [message: "Doctest failed: expected exception #{spec} but got #{got}",
-               expr: expr],
-              stack
+          actual_exception = error.__struct__
+          actual_message = Exception.message(error)
+          message =
+            cond do
+              actual_exception != unquote(exception) ->
+                "Doctest failed: expected exception #{inspect(unquote(exception))} but got #{inspect(actual_exception)} with message #{inspect(actual_message)}"
+              actual_message != unquote(message) ->
+                "Doctest failed: wrong message for #{inspect(actual_exception)}\n" <>
+                  "expected:\n" <>
+                  "  #{inspect(unquote(message))}\n" <>
+                  "actual:\n" <>
+                  "  #{inspect(actual_message)}"
+              true ->
+                nil
+            end
+
+          if message do
+            reraise ExUnit.AssertionError, [message: message, expr: expr], stack
           end
       else
         _ ->
           reraise ExUnit.AssertionError,
-            [message: "Doctest failed: expected exception #{spec} but nothing was raised",
+            [message: "Doctest failed: expected exception #{inspect(unquote(exception))} but nothing was raised",
              expr: expr],
             stack
       end

lib/ex_unit/test/ex_unit/assertions_test.exs

@@ -453,9 +453,9 @@ defmodule ExUnit.AssertionsTest do
   rescue
     error in [ExUnit.AssertionError] ->
       "Wrong message for RuntimeError" <>
-      "\nExpected:" <>
+      "\nexpected:" <>
       "\n  \"foo\"" <>
-      "\nGot:" <>
+      "\nactual:" <>
       "\n  \"bar\"" = error.message
   end
 
@@ -466,9 +466,9 @@ defmodule ExUnit.AssertionsTest do
   rescue
     error in [ExUnit.AssertionError] ->
       "Wrong message for RuntimeError" <>
-      "\nExpected:" <>
+      "\nexpected:" <>
       "\n  ~r/ba[zk]/" <>
-      "\nGot:" <>
+      "\nactual:" <>
       "\n  \"bar\"" = error.message
   end
 

lib/ex_unit/test/ex_unit/doc_test_test.exs

@@ -298,7 +298,7 @@ defmodule ExUnit.DocTestTest do
     assert output =~ """
       5) test moduledoc at ExUnit.DocTestTest.Invalid (5) (ExUnit.DocTestTest.ActuallyCompiled)
          test/ex_unit/doc_test_test.exs:248
-         Doctest failed: expected exception WhatIsThis with message "oops" but got RuntimeError with message "oops"
+         Doctest failed: expected exception WhatIsThis but got RuntimeError with message "oops"
          code: raise "oops"
          stacktrace:
            test/ex_unit/doc_test_test.exs:139: ExUnit.DocTestTest.Invalid (module)
@@ -307,7 +307,11 @@ defmodule ExUnit.DocTestTest do
     assert output =~ """
       6) test moduledoc at ExUnit.DocTestTest.Invalid (6) (ExUnit.DocTestTest.ActuallyCompiled)
          test/ex_unit/doc_test_test.exs:248
-         Doctest failed: expected exception RuntimeError with message "hello" but got RuntimeError with message "oops"
+         Doctest failed: wrong message for RuntimeError
+         expected:
+           "hello"
+         actual:
+           "oops"
          code: raise "oops"
          stacktrace:
            test/ex_unit/doc_test_test.exs:142: ExUnit.DocTestTest.Invalid (module)