Add ExUnit.run/1 to rerun test modules

lib/ex_unit/lib/ex_unit.ex

@@ -350,11 +350,25 @@ defmodule ExUnit do
   Runs the tests. It is invoked automatically
   if ExUnit is started via `start/1`.
 
+  From Elixir v1.14, it accepts an optional list of modules to run
+  as part of the suite. This is often used to rerun modules already
+  loaded in memory.
+
   Returns a map containing the total number of tests, the number
   of failures, the number of excluded tests and the number of skipped tests.
   """
-  @spec run() :: suite_result()
-  def run do
+  @spec run(list(atom)) :: suite_result()
+  def run(additional_modules \\ []) do
+    for module <- additional_modules do
+      module_attributes = module.__info__(:attributes)
+
+      if Keyword.get(module_attributes, :ex_unit_async) do
+        ExUnit.Server.add_async_module(module)
+      else
+        ExUnit.Server.add_sync_module(module)
+      end
+    end
+
     _ = ExUnit.Server.modules_loaded()
     options = persist_defaults(configuration())
     ExUnit.Runner.run(options, nil)

lib/ex_unit/lib/ex_unit/case.ex

@@ -294,6 +294,9 @@ defmodule ExUnit.Case do
 
       Enum.each(attributes, &Module.register_attribute(module, &1, accumulate: true))
 
+      persisted_attributes = [:ex_unit_async]
+      Enum.each(persisted_attributes, &Module.register_attribute(module, &1, persist: true))
+
       attributes = [
         before_compile: ExUnit.Case,
         after_compile: ExUnit.Case,

lib/ex_unit/test/ex_unit_test.exs

@@ -32,6 +32,52 @@ defmodule ExUnitTest do
            end) =~ "\n0 failures\n"
   end
 
+  test "supports rerunning given modules" do
+    defmodule SampleAsyncTest do
+      use ExUnit.Case, async: true
+
+      test "true" do
+        assert false
+      end
+    end
+
+    defmodule SampleSyncTest do
+      use ExUnit.Case
+
+      test "true" do
+        assert false
+      end
+    end
+
+    defmodule IgnoreTest do
+      use ExUnit.Case
+
+      test "true" do
+        assert false
+      end
+    end
+
+    configure_and_reload_on_exit([])
+
+    assert capture_io(fn ->
+             assert ExUnit.run() == %{
+                      failures: 3,
+                      skipped: 0,
+                      total: 3,
+                      excluded: 0
+                    }
+           end) =~ "\n3 tests, 3 failures\n"
+
+    assert capture_io(fn ->
+             assert ExUnit.run([SampleSyncTest, SampleAsyncTest]) == %{
+                      failures: 2,
+                      skipped: 0,
+                      total: 2,
+                      excluded: 0
+                    }
+           end) =~ "\n2 tests, 2 failures\n"
+  end
+
   test "prints aborted runs on sigquit", config do
     Process.register(self(), :aborted_on_sigquit)
     line = __ENV__.line + 5