TEST: remove very slow test, add it as a comment to the code snippet it tests

2 files changed, 18 insertions, 28 deletions

diff --git a/numpy/core/src/multiarray/convert.c b/numpy/core/src/multiarray/convert.c
index ef231587d..e99bc3fe4 100644
--- a/numpy/core/src/multiarray/convert.c
+++ b/numpy/core/src/multiarray/convert.c
@@ -157,7 +157,24 @@ PyArray_ToFile(PyArrayObject *self, FILE *fp, char *sep, char *format)
             NPY_BEGIN_ALLOW_THREADS;
 
 #if defined (_MSC_VER) && defined(_WIN64)
-            /* Workaround Win64 fwrite() bug. Ticket #1660 */
+            /* Workaround Win64 fwrite() bug. Issue gh-2556
+             * If you touch this code, please run this test which is so slow
+             * it was removed from the test suite
+             *
+             * fourgbplus = 2**32 + 2**16
+             * testbytes = np.arange(8, dtype=np.int8)
+             * n = len(testbytes)
+             * flike = tempfile.NamedTemporaryFile()
+             * f = flike.file
+             * np.tile(testbytes, fourgbplus // testbytes.nbytes).tofile(f)
+             * flike.seek(0)
+             * a = np.fromfile(f, dtype=np.int8)
+             * flike.close()
+             * assert_(len(a) == fourgbplus)
+             * # check only start and end for speed:
+             * assert_((a[:n] == testbytes).all())
+             * assert_((a[-n:] == testbytes).all())
+             */
             {
                 npy_intp maxsize = 2147483648 / PyArray_DESCR(self)->elsize;
                 npy_intp chunksize;
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 2d6f9c38c..422edf9a7 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -5552,33 +5552,6 @@ class TestIO:
             tmp_filename,
             dtype='<f4')
 
-    @pytest.mark.slow  # takes > 1 minute on mechanical hard drive
-    def test_big_binary(self):
-        """Test workarounds for 32-bit limit for MSVC fwrite, fseek, and ftell
-
-        These normally would hang doing something like this.
-        See : https://github.com/numpy/numpy/issues/2256
-        """
-        if sys.platform != 'win32' or '[GCC ' in sys.version:
-            return
-        try:
-            # before workarounds, only up to 2**32-1 worked
-            fourgbplus = 2**32 + 2**16
-            testbytes = np.arange(8, dtype=np.int8)
-            n = len(testbytes)
-            flike = tempfile.NamedTemporaryFile()
-            f = flike.file
-            np.tile(testbytes, fourgbplus // testbytes.nbytes).tofile(f)
-            flike.seek(0)
-            a = np.fromfile(f, dtype=np.int8)
-            flike.close()
-            assert_(len(a) == fourgbplus)
-            # check only start and end for speed:
-            assert_((a[:n] == testbytes).all())
-            assert_((a[-n:] == testbytes).all())
-        except (MemoryError, ValueError):
-            pass
-
     def test_string(self, tmp_filename):
         self._check_from(b'1,2,3,4', [1., 2., 3., 4.], tmp_filename, sep=',')