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

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

testing/acceptance_test.py

@@ -262,6 +262,16 @@ class TestDistribution:
         child.close()
         # assert ret == 2
 
+    def test_dist_with_collectonly(self, testdir):
+        p1 = testdir.makepyfile("""
+            def test_ok():
+                pass
+        """)
+        result = testdir.runpytest(p1, "-n1", "--collect-only")
+        assert result.ret == 0
+        result.stdout.fnmatch_lines([
+            "*collected 1 item*",
+        ])
 
 class TestDistEach:
     def test_simple(self, testdir):

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):

xdist/plugin.py

@@ -91,15 +91,14 @@ def pytest_addhooks(pluginmanager):
 
 @pytest.mark.trylast
 def pytest_configure(config):
-    if not config.getvalue("collectonly"):
-        if config.getoption("dist") != "no":
-            from xdist.dsession import DSession
-            session = DSession(config)
-            config.pluginmanager.register(session, "dsession")
-            tr = config.pluginmanager.getplugin("terminalreporter")
-            tr.showfspath = False
-        if config.getoption("boxed"):
-            config.option.forked = True
+    if config.getoption("dist") != "no" and not config.getvalue("collectonly"):
+        from xdist.dsession import DSession
+        session = DSession(config)
+        config.pluginmanager.register(session, "dsession")
+        tr = config.pluginmanager.getplugin("terminalreporter")
+        tr.showfspath = False
+    if config.getoption("boxed"):
+        config.option.forked = True
 
 
 @pytest.mark.tryfirst