4 files changed, 41 insertions, 46 deletions
diff --git a/test/serd_test_util/__init__.py b/test/serd_test_util/__init__.py
index 8027462b..ad417762 100644
--- a/test/serd_test_util/__init__.py
+++ b/test/serd_test_util/__init__.py
@@ -8,10 +8,12 @@
 # pylint: disable=consider-using-f-string
 # pylint: disable=invalid-name
 
+import argparse
 import datetime
 import difflib
 import os
 import re
+import shlex
 import subprocess
 import sys
 import urllib.parse
@@ -51,6 +53,33 @@ def error(message):
     sys.stderr.write("\n")
 
 
+def wrapper_args(description, with_input=False):
+    """Return the command line arguments for a wrapped test."""
+
+    parser = argparse.ArgumentParser(description)
+    parser.add_argument("--serdi", default="./serdi", help="serdi executable")
+    parser.add_argument("--wrapper", default="", help="executable wrapper")
+    if with_input:
+        parser.add_argument("input", help="input file")
+
+    return parser.parse_args(sys.argv[1:])
+
+
+def command_output(wrapper, command, stdin=None):
+    """Run a command and check that stdout matches the expected output."""
+
+    proc = subprocess.run(
+        shlex.split(wrapper) + command,
+        capture_output=True,
+        check=True,
+        encoding="utf-8",
+        input=stdin,
+    )
+
+    assert wrapper or not proc.stderr
+    return proc.stdout
+
+
 def print_result_summary(results):
     """Print test result summary to stdout or stderr as appropriate."""
 
diff --git a/test/test_quiet.py b/test/test_quiet.py
index 42d05785..676284bb 100755
--- a/test/test_quiet.py
+++ b/test/test_quiet.py
@@ -3,20 +3,14 @@
 # Copyright 2022 David Robillard <d@drobilla.net>
 # SPDX-License-Identifier: ISC
 
-"""Test serdi quiet option."""
+"""Test quiet command-line option."""
 
-import argparse
-import sys
 import shlex
 import subprocess
 
-parser = argparse.ArgumentParser(description=__doc__)
+import serd_test_util as util
 
-parser.add_argument("--serdi", default="./serdi", help="path to serdi")
-parser.add_argument("--wrapper", default="", help="executable wrapper")
-parser.add_argument("input", help="invalid input file")
-
-args = parser.parse_args(sys.argv[1:])
+args = util.wrapper_args(__doc__, True)
 command = shlex.split(args.wrapper) + [args.serdi, "-q", args.input]
 proc = subprocess.run(
     command, check=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE
diff --git a/test/test_stdin.py b/test/test_stdin.py
index f976ca52..fb01f4ee 100755
--- a/test/test_stdin.py
+++ b/test/test_stdin.py
@@ -7,37 +7,14 @@
 
 # pylint: disable=consider-using-f-string
 
-import argparse
-import sys
-import shlex
-import subprocess
-import tempfile
+import serd_test_util as util
 
-parser = argparse.ArgumentParser(description=__doc__)
+args = util.wrapper_args(__doc__)
+command = [args.serdi, "-i", "ntriples", "-", "http://example.org"]
 
-parser.add_argument("--serdi", default="./serdi", help="path to serdi")
-parser.add_argument("--wrapper", default="", help="executable wrapper")
+DOC = "<{0}s> <{0}p> <{0}o> .".format("http://example.org/")
 
-args = parser.parse_args(sys.argv[1:])
-command = shlex.split(args.wrapper) + [args.serdi, "-"]
+lines = util.command_output(args.wrapper, command, DOC).splitlines(True)
 
-DOCUMENT = "<{0}s> <{0}p> <{0}o> .".format("http://example.org/")
-
-with tempfile.TemporaryFile() as out:
-    proc = subprocess.run(
-        command,
-        check=False,
-        encoding="utf-8",
-        input=DOCUMENT,
-        stdout=out,
-        stderr=subprocess.PIPE,
-    )
-
-    assert proc.returncode == 0
-    assert args.wrapper or len(proc.stderr) == 0
-
-    out.seek(0)
-    lines = out.readlines()
-
-    assert len(lines) == 1
-    assert lines[0].decode("utf-8").strip() == DOCUMENT
+assert len(lines) == 1
+assert lines[0].strip() == DOC
diff --git a/test/test_write_error.py b/test/test_write_error.py
index 35fde232..b62f981a 100755
--- a/test/test_write_error.py
+++ b/test/test_write_error.py
@@ -5,19 +5,14 @@
 
 """Test errors writing to a file."""
 
-import argparse
 import sys
 import shlex
 import subprocess
 import os
 
-parser = argparse.ArgumentParser(description=__doc__)
+import serd_test_util as util
 
-parser.add_argument("--serdi", default="./serdi", help="path to serdi")
-parser.add_argument("--wrapper", default="", help="executable wrapper")
-parser.add_argument("input", help="valid input file")
-
-args = parser.parse_args(sys.argv[1:])
+args = util.wrapper_args(__doc__, True)
 command = shlex.split(args.wrapper) + [args.serdi, args.input]
 
 if os.path.exists("/dev/full"):