Add raw string compare in doctests for #Module<...>

Will now do raw string compare for doctests of #Module<...> format:

    iex> HashDict.new a: 0, b: 1, c: 2
    #HashDict<[a: 0, b: 1, c: 2]>

Author: ericmj

lib/elixir/lib/version.ex

@@ -140,7 +140,7 @@ defmodule Version do
 
   ## Examples
 
-      > Version.parse("2.0.1-alpha1")
+      iex> Version.parse("2.0.1-alpha1")
       #Version.Schema<2.0.1-alpha1>
 
   """
@@ -193,7 +193,7 @@ defmodule Version do
 
   ## Examples
 
-      > Version.from_matchable({2, 0, 1, ["alpha", 1]})
+      iex> Version.from_matchable({2, 0, 1, ["alpha", 1]})
       #Version.Schema<2.0.1-alpha.1>
 
   """

lib/ex_unit/lib/ex_unit/doc_test.ex

@@ -74,6 +74,19 @@ defmodule ExUnit.DocTest do
   We also allow you to select or skip some functions when calling
   `doctest`. See the documentation for more info.
 
+  ## Opaque types
+
+  Some types internal structure are kept hidden and instead show a
+  user-friendly structure when inspecting the value. The idiom in
+  Elixir is to print those data types as `#Name<...>`. Doctest will
+  test these values by doing a string compare.
+
+      iex> HashDict.new(a: 10, b: 20)
+      #HashDict<[a: 10, b: 20]>
+
+  The above example will be tested with the following match:
+  `"#HashDict<[a: 10, b: 20]>" = inspect (HashDict.new(a: 10, b: 20))`.
+
   ## Exceptions
 
   You can also showcase expressions raising an exception, for example:
@@ -260,6 +273,27 @@ defmodule ExUnit.DocTest do
     end
   end
 
+  defp test_case_content(expr, { :inspect, expected }, module, line, file, stack) do
+    expr_ast     = string_to_quoted(module, line, file, expr)
+    expr_ast     = quote do: inspect(unquote(expr_ast))
+    expected_ast = string_to_quoted(module, line, file, expected)
+
+    quote do
+      v = unquote(expected_ast)
+      case unquote(expr_ast) do
+        ^v -> :ok
+        actual ->
+          raise ExUnit.ExpectationError,
+            [ prelude: "Expected doctest",
+              expr: unquote(expr),
+              expected: inspect(v),
+              assertion: "inspect as",
+              actual: inspect(actual) ],
+            unquote(stack)
+      end
+    end
+  end
+
   defp test_case_content(expr, { :error, exception, message }, module, line, file, stack) do
     expr_ast = string_to_quoted(module, line, file, expr)
 
@@ -468,8 +502,14 @@ defmodule ExUnit.DocTest do
   end
 
   # Finally, parse expected_acc.
-  defp extract_tests([expected|lines], line, expr_acc, expected_acc, acc, newtest) do
-    extract_tests(lines, line, expr_acc, expected_acc <> "\n" <> expected, acc, newtest)
+  defp extract_tests([expected|lines], line, expr_acc, expected_acc, [test=Test[exprs: exprs]|t]=acc, newtest) do
+    if expected =~ %r/^#[A-Z][\w\.]*<.*>$/ do
+      expected = expected_acc <> "\n" <> Inspect.BitString.inspect(expected, [])
+      test = test.exprs([{ expr_acc, { :inspect, expected } } | exprs])
+      extract_tests(lines, line,  "", "", [test|t], newtest)
+    else
+      extract_tests(lines, line, expr_acc, expected_acc <> "\n" <> expected, acc, newtest)
+    end
   end
 
   defp extract_error(<< ")", t :: binary >>, acc) do

lib/ex_unit/test/ex_unit/doc_test_test.exs

@@ -32,6 +32,19 @@ defmodule ExUnit.DocTestTest.GoodModule do
   ** (ArithmeticError) bad argument in arithmetic expression
   """
   def exception_test, do: :ok
+
+  @doc """
+  iex> HashDict.new a: 0, b: 1, c: 2
+  #HashDict<[a: 0, b: 1, c: 2]>
+  """
+  def inspect1_test, do: :ok
+
+  @doc """
+  iex> x = HashDict.new a: 0, b: 1, c: 2
+  ...> x
+  #HashDict<[a: 0, b: 1, c: 2]>
+  """
+  def inspect2_test, do: :ok
 end
 
 defmodule ExUnit.DocTestTest.ExceptionModule do