Add tests for interactions between boxed, dist and collect-only.

Re-enable parsing of the boxed option with collect-only

testing/test_plugin.py

@@ -43,6 +43,33 @@ def test_auto_detect_cpus(testdir, monkeypatch):
     config = testdir.parseconfigure("-nauto")
     assert config.getoption('numprocesses') == 99
 
+def test_boxed_with_collect_only(testdir):
+    from xdist.plugin import pytest_cmdline_main as check_options
+    config = testdir.parseconfigure("-n1", "--boxed")
+    check_options(config)
+    assert config.option.forked
+
+    config = testdir.parseconfigure("-n1", "--collect-only")
+    check_options(config)
+    assert not config.option.forked
+
+    config = testdir.parseconfigure("-n1", "--boxed", "--collect-only")
+    check_options(config)
+    assert config.option.forked
+
+def test_dsession_with_collect_only(testdir):
+    from xdist.plugin import pytest_cmdline_main as check_options
+    from xdist.plugin import pytest_configure as configure
+
+    config = testdir.parseconfigure("-n1")
+    check_options(config)
+    configure(config)
+    assert config.pluginmanager.hasplugin("dsession")
+
+    config = testdir.parseconfigure("-n1", "--collect-only")
+    check_options(config)
+    configure(config)
+    assert not config.pluginmanager.hasplugin("dsession")
 
 class TestDistOptions:
     def test_getxspecs(self, testdir):