initial copy and modifications from the original py/impl/test/dist and

looponfail code. Now works as its own "xdist" plugin.

testing/test_boxed.py

@@ -0,0 +1,30 @@
+import py
+
+@py.test.mark.skipif("not hasattr(os, 'fork')")
+def test_functional_boxed(testdir):
+    p1 = testdir.makepyfile("""
+        import os
+        def test_function():
+            os.kill(os.getpid(), 15)
+    """)
+    result = testdir.runpytest(p1, "--boxed")
+    assert result.stdout.fnmatch_lines([
+        "*CRASHED*",
+        "*1 failed*"
+    ])
+
+class TestOptionEffects:
+    def test_boxed_option_default(self, testdir):
+        tmpdir = testdir.tmpdir.ensure("subdir", dir=1)
+        config = testdir.reparseconfig()
+        config.initsession()
+        assert not config.option.boxed
+        py.test.importorskip("execnet")
+        config = testdir.reparseconfig(['-d', tmpdir])
+        config.initsession()
+        assert not config.option.boxed
+
+    def test_is_not_boxed_by_default(self, testdir):
+        config = testdir.reparseconfig([testdir.tmpdir])
+        assert not config.option.boxed
+