feat: treat non-seekable files as pipes (#2309)

Previously, attempting to read from a pipe would result in an error:
'not a regular file', disallowing use of files like /dev/stdin or
/dev/fd/3, named fifos, sockets, etc.

The tools already understand how to (try to) read from non-regular
files, so this change attempts to do so when the input is not seek-able
(the "regular file" capability that's in use here).

Additionally, this adds a test for the new behavior using a bash
herestring and process substitution (the latter of which shows up in
argv as something like `/dev/fd/NN`). Since bash isn't commonly
installed on Windows, this change also introduces a new capability to
filter tests to specific platforms (sorry).

1 files changed, 3 insertions, 0 deletions

diff --git a/test/run-tests.py b/test/run-tests.py
index 0bd241ea..370f75ef 100755
--- a/test/run-tests.py
+++ b/test/run-tests.py
@@ -20,6 +20,7 @@ import difflib
 import fnmatch
 import multiprocessing
 import os
+import platform
 import re
 import shlex
 import shutil
@@ -505,6 +506,8 @@ class TestInfo(object):
         elif key == 'ENV':
             # Pattern: FOO=1 BAR=stuff
             self.env = dict(x.split('=') for x in value.split())
+        elif key == 'PLATFORMS':
+            self.skip = platform.system() not in value.split()
         else:
             raise Error('Unknown directive: %s' % key)