Show specific description for dont_display_result atom in i/1 helper (#6137)

:"do not show this result in output" is the returned value of functions
that print to screen and do not want to show their returned value on
screen.

This commit adds information about that particular atom to the
i/1 IEx helper.

2 files changed, 25 insertions, 2 deletions

diff --git a/lib/iex/lib/iex/info.ex b/lib/iex/lib/iex/info.ex
index 45f9780ab..d5f2b28c7 100644
--- a/lib/iex/lib/iex/info.ex
+++ b/lib/iex/lib/iex/info.ex
@@ -23,7 +23,17 @@ defimpl IEx.Info, for: Atom do
         true ->
           info_atom(atom)
       end
-    ["Data type": "Atom"] ++ specific_info
+
+    description =
+      if atom == IEx.dont_display_result() do
+        ["Description": """
+        This atom is returned by IEx when a function that should not print its
+        return value on screen is executed.
+        """]
+      else
+        []
+      end
+    ["Data type": "Atom"] ++ description ++ specific_info
   end
 
   defp info_module(mod) do
diff --git a/lib/iex/test/iex/helpers_test.exs b/lib/iex/test/iex/helpers_test.exs
index 2059754c3..4a99fb9ab 100644
--- a/lib/iex/test/iex/helpers_test.exs
+++ b/lib/iex/test/iex/helpers_test.exs
@@ -484,7 +484,7 @@ defmodule IEx.HelpersTest do
     end
   end
 
-  test "i helper" do
+  test "i/1 helper" do
     output = capture_io fn -> i(:ok) end
     assert output =~ String.trim_trailing("""
     Term
@@ -496,6 +496,19 @@ defmodule IEx.HelpersTest do
     """)
   end
 
+  test "i/1 helper on functions that don't display result" do
+    output = capture_io fn -> i(IEx.dont_display_result()) end
+    assert output =~ String.trim_trailing("""
+    Term
+      :"do not show this result in output"
+    Data type
+      Atom
+    Description
+      This atom is returned by IEx when a function that should not print its
+      return value on screen is executed.
+    """)
+  end
+
   defp test_module_code do
     """
     defmodule Sample do