ttx_test: test dumping and compiling from stdin to stdout

Tests/ttx/ttx_test.py

@@ -6,9 +6,11 @@ import getopt
 import logging
 import os
 import shutil
+import subprocess
 import sys
 import tempfile
 import unittest
+from pathlib import Path
 
 import pytest
 
@@ -996,6 +998,24 @@ def test_main_base_exception(tmpdir, monkeypatch, caplog):
     assert "Unhandled exception has occurred" in caplog.text
 
 
+def test_main_ttf_dump_stdin_to_stdout(tmp_path):
+    inpath = Path("Tests").joinpath("ttx", "data", "TestTTF.ttf")
+    outpath = tmp_path / "TestTTF.ttx"
+    args = [sys.executable, "-m", "fontTools.ttx", "-q", "-o", "-", "-"]
+    with inpath.open("rb") as infile, outpath.open("w", encoding="utf-8") as outfile:
+        subprocess.run(args, check=True, stdin=infile, stdout=outfile)
+    assert outpath.is_file()
+
+
+def test_main_ttx_compile_stdin_to_stdout(tmp_path):
+    inpath = Path("Tests").joinpath("ttx", "data", "TestTTF.ttx")
+    outpath = tmp_path / "TestTTF.ttf"
+    args = [sys.executable, "-m", "fontTools.ttx", "-q", "-o", "-", "-"]
+    with inpath.open("r", encoding="utf-8") as infile, outpath.open("wb") as outfile:
+        subprocess.run(args, check=True, stdin=infile, stdout=outfile)
+    assert outpath.is_file()
+
+
 # ---------------------------
 # support functions for tests
 # ---------------------------