Slows Test Output, Example Output: https://gist.github.com/bjfish/1bd194865317e5f63ae831f10fc0e118

slow_test.patch

diff --git a/lib/ex_unit/lib/ex_unit/cli_formatter.ex b/lib/ex_unit/lib/ex_unit/cli_formatter.ex
index a8f3504..cc72acc 100644
--- a/lib/ex_unit/lib/ex_unit/cli_formatter.ex
+++ b/lib/ex_unit/lib/ex_unit/cli_formatter.ex
@@ -18,7 +18,8 @@ defmodule ExUnit.CLIFormatter do
       tests_counter: 0,
       failures_counter: 0,
       skipped_counter: 0,
-      invalids_counter: 0
+      invalids_counter: 0,
+      results: []
     }
     {:ok, config}
   end
@@ -29,6 +30,7 @@ defmodule ExUnit.CLIFormatter do
 
   def handle_event({:suite_finished, run_us, load_us}, config) do
     print_suite(config, run_us, load_us)
+    trace_test_times(config)
     :remove_handler
   end
 
@@ -43,7 +45,7 @@ defmodule ExUnit.CLIFormatter do
     else
       IO.write success(".", config)
     end
-    {:ok, %{config | tests_counter: config.tests_counter + 1}}
+    {:ok, %{config | tests_counter: config.tests_counter + 1, results: [ test | config.results ]}}
   end
 
   def handle_event({:test_finished, %ExUnit.Test{state: {:skip, _}} = test}, config) do
@@ -74,7 +76,7 @@ defmodule ExUnit.CLIFormatter do
     print_logs(test.logs)
 
     {:ok, %{config | tests_counter: config.tests_counter + 1,
-                     failures_counter: config.failures_counter + 1}}
+                     failures_counter: config.failures_counter + 1, results: [ test | config.results ]}}
   end
 
   def handle_event({:case_started, %ExUnit.TestCase{name: name}}, config) do
@@ -97,6 +99,27 @@ defmodule ExUnit.CLIFormatter do
   end
 
   ## Tracing
+  def trace_test_times(config) do
+    results = Enum.filter(config.results, fn(test) -> test.time > 100_000 end)
+    results = Enum.reverse( Enum.sort_by(results, fn(test) -> test.time end) )
+    length_longest_name = Enum.reduce(results, 0, fn(test, acc) ->
+      len = String.length(test_case_name(test))
+      if len > acc, do: len, else: acc
+    end)
+    longest_time = Enum.reduce(results, 0, fn(test, acc) ->
+      len = String.length(trace_test_time(test))
+      if len > acc, do: len, else: acc
+    end)
+
+    Enum.each( results, fn(test) ->
+        IO.puts(String.ljust(test_case_name(test), length_longest_name + 1) <>
+                String.rjust(trace_test_time(test), longest_time))
+    end)
+  end
+
+  defp test_case_name(%ExUnit.Test{case: case } = test) do
+    "#{inspect case} #{trace_test_name test}"
+  end
 
   defp trace_test_name(%ExUnit.Test{name: name}) do
     case Atom.to_string(name) do