tests/testutils/runcli.py: Support binary-mode capture of stdout

In order to test things which write tarballs to stdout correctly,
we need to capture the binary output cleanly.  This ensures we're not
potentially mismatching encodings in and out.

Signed-off-by: Daniel Silverstone <daniel.silverstone@codethink.co.uk>

1 files changed, 7 insertions, 6 deletions

diff --git a/tests/testutils/runcli.py b/tests/testutils/runcli.py
index 3535e94ea..ce5864bdf 100644
--- a/tests/testutils/runcli.py
+++ b/tests/testutils/runcli.py
@@ -17,7 +17,7 @@ import pytest
 # CliRunner convenience API (click.testing module) does not support
 # separation of stdout/stderr.
 #
-from _pytest.capture import MultiCapture, FDCapture
+from _pytest.capture import MultiCapture, FDCapture, FDCaptureBinary
 
 # Import the main cli entrypoint
 from buildstream._frontend import cli as bst_cli
@@ -234,9 +234,10 @@ class Cli():
     #    silent (bool): Whether to pass --no-verbose
     #    env (dict): Environment variables to temporarily set during the test
     #    args (list): A list of arguments to pass buildstream
+    #    binary_capture (bool): Whether to capture the stdout/stderr as binary
     #
     def run(self, configure=True, project=None, silent=False, env=None,
-            cwd=None, options=None, args=None):
+            cwd=None, options=None, args=None, binary_capture=False):
         if args is None:
             args = []
         if options is None:
@@ -278,7 +279,7 @@ class Cli():
             except ValueError:
                 sys.__stdout__ = open('/dev/stdout', 'w')
 
-            result = self.invoke(bst_cli, bst_args)
+            result = self.invoke(bst_cli, bst_args, binary_capture=binary_capture)
 
         # Some informative stdout we can observe when anything fails
         if self.verbose:
@@ -295,7 +296,7 @@ class Cli():
 
         return result
 
-    def invoke(self, cli, args=None, color=False, **extra):
+    def invoke(self, cli, args=None, color=False, binary_capture=False, **extra):
         exc_info = None
         exception = None
         exit_code = 0
@@ -305,8 +306,8 @@ class Cli():
         old_stdin = sys.stdin
         with open(os.devnull) as devnull:
             sys.stdin = devnull
-
-            capture = MultiCapture(out=True, err=True, in_=False, Capture=FDCapture)
+            capture_kind = FDCaptureBinary if binary_capture else FDCapture
+            capture = MultiCapture(out=True, err=True, in_=False, Capture=capture_kind)
             capture.start_capturing()
 
             try: