1 files changed, 39 insertions, 2 deletions
diff --git a/numpy/distutils/tests/test_fcompiler.py b/numpy/distutils/tests/test_fcompiler.py
index 95e44b051..ba19a97ea 100644
--- a/numpy/distutils/tests/test_fcompiler.py
+++ b/numpy/distutils/tests/test_fcompiler.py
@@ -1,6 +1,8 @@
 from __future__ import division, absolute_import, print_function
 
-from numpy.testing import assert_
+import pytest
+
+from numpy.testing import assert_, suppress_warnings
 import numpy.distutils.fcompiler
 
 customizable_flags = [
@@ -25,6 +27,7 @@ def test_fcompiler_flags(monkeypatch):
 
         monkeypatch.setenv(envvar, new_flag)
         new_flags = getattr(flag_vars, opt)
+
         monkeypatch.delenv(envvar)
         assert_(new_flags == [new_flag])
 
@@ -33,12 +36,46 @@ def test_fcompiler_flags(monkeypatch):
     for opt, envvar in customizable_flags:
         new_flag = '-dummy-{}-flag'.format(opt)
         prev_flags = getattr(flag_vars, opt)
-
         monkeypatch.setenv(envvar, new_flag)
         new_flags = getattr(flag_vars, opt)
+
         monkeypatch.delenv(envvar)
         if prev_flags is None:
             assert_(new_flags == [new_flag])
         else:
             assert_(new_flags == prev_flags + [new_flag])
 
+
+def test_fcompiler_flags_append_warning(monkeypatch):
+    # Test to check that the warning for append behavior changing in future
+    # is triggered.  Need to use a real compiler instance so that we have
+    # non-empty flags to start with (otherwise the "if var and append" check
+    # will always be false).
+    try:
+        with suppress_warnings() as sup:
+            sup.record()
+            fc = numpy.distutils.fcompiler.new_fcompiler(compiler='gnu95')
+            fc.customize()
+    except numpy.distutils.fcompiler.CompilerNotFound:
+        pytest.skip("gfortran not found, so can't execute this test")
+
+    # Ensure NPY_DISTUTILS_APPEND_FLAGS not defined
+    monkeypatch.delenv('NPY_DISTUTILS_APPEND_FLAGS', raising=False)
+
+    for opt, envvar in customizable_flags:
+        new_flag = '-dummy-{}-flag'.format(opt)
+        with suppress_warnings() as sup:
+            sup.record()
+            prev_flags = getattr(fc.flag_vars, opt)
+
+        monkeypatch.setenv(envvar, new_flag)
+        with suppress_warnings() as sup:
+            sup.record()
+            new_flags = getattr(fc.flag_vars, opt)
+            if prev_flags:
+                # Check that warning was issued
+                assert len(sup.log) == 1
+
+        monkeypatch.delenv(envvar)
+        assert_(new_flags == [new_flag])
+