1 files changed, 34 insertions, 1 deletions
diff --git a/numpy/distutils/tests/test_system_info.py b/numpy/distutils/tests/test_system_info.py
index 0768ffdde..ec15126f7 100644
--- a/numpy/distutils/tests/test_system_info.py
+++ b/numpy/distutils/tests/test_system_info.py
@@ -284,4 +284,37 @@ class TestSystemInfoReading:
             assert info.get_lib_dirs() == lib_dirs
         finally:
             os.chdir(previousDir)
-        
+
+
+def test_distutils_parse_env_order(monkeypatch):
+    from numpy.distutils.system_info import _parse_env_order
+    env = 'NPY_TESTS_DISTUTILS_PARSE_ENV_ORDER'
+
+    base_order = list('abcdef')
+
+    monkeypatch.setenv(env, 'b,i,e,f')
+    order, unknown = _parse_env_order(base_order, env)
+    assert len(order) == 3
+    assert order == list('bef')
+    assert len(unknown) == 1
+
+    # For when LAPACK/BLAS optimization is disabled
+    monkeypatch.setenv(env, '')
+    order, unknown = _parse_env_order(base_order, env)
+    assert len(order) == 0
+    assert len(unknown) == 0
+
+    for prefix in '^!':
+        monkeypatch.setenv(env, f'{prefix}b,i,e')
+        order, unknown = _parse_env_order(base_order, env)
+        assert len(order) == 4
+        assert order == list('acdf')
+        assert len(unknown) == 1
+
+    with pytest.raises(ValueError):
+        monkeypatch.setenv(env, 'b,^e,i')
+        _parse_env_order(base_order, env)
+
+    with pytest.raises(ValueError):
+        monkeypatch.setenv(env, '!b,^e,i')
+        _parse_env_order(base_order, env)