Revert "Merge pull request #560 from utapyngo/logical-cpu-count"

This reverts commit 0094b29a14, reversing
changes made to c6255faad4.

testing/test_plugin.py

@@ -35,10 +35,17 @@ def test_dist_options(testdir):
 
 
 def test_auto_detect_cpus(testdir, monkeypatch):
-    import psutil
+    import os
     from xdist.plugin import pytest_cmdline_main as check_options
 
-    monkeypatch.setattr(psutil, "cpu_count", lambda logical=True: 99)
+    if hasattr(os, "sched_getaffinity"):
+        monkeypatch.setattr(os, "sched_getaffinity", lambda _pid: set(range(99)))
+    elif hasattr(os, "cpu_count"):
+        monkeypatch.setattr(os, "cpu_count", lambda: 99)
+    else:
+        import multiprocessing
+
+        monkeypatch.setattr(multiprocessing, "cpu_count", lambda: 99)
 
     config = testdir.parseconfigure("-n2")
     assert config.getoption("numprocesses") == 2
@@ -52,9 +59,10 @@ def test_auto_detect_cpus(testdir, monkeypatch):
     assert config.getoption("numprocesses") == 0
     assert config.getoption("dist") == "no"
 
-    monkeypatch.setattr(psutil, "cpu_count", lambda logical=True: None)
+    monkeypatch.delattr(os, "sched_getaffinity", raising=False)
+    monkeypatch.setenv("TRAVIS", "true")
     config = testdir.parseconfigure("-nauto")
-    assert config.getoption("numprocesses") == 1
+    assert config.getoption("numprocesses") == 2
 
 
 def test_boxed_with_collect_only(testdir):