don't use global configuration

tests/test_audio.py

@@ -0,0 +1,29 @@
+from amodem import audio
+import subprocess as sp
+import signal
+
+
+def test_launch():
+    p = audio.ALSA(tool='true', Fs=32000).launch(fname='fname')
+    assert p.wait() == 0
+
+def test_exit():
+    p = audio.ALSA(tool='python', Fs=32000).launch(fname='-', stdin=sp.PIPE)
+    s = b'import sys; sys.exit(42)'
+    p.stdin.write(s)
+    p.stdin.close()
+    assert p.wait() == 42
+
+def test_io():
+    p = audio.ALSA(tool='python', Fs=32000)
+    p = p.launch(fname='-', stdin=sp.PIPE, stdout=sp.PIPE)
+    s = b'Hello World!'
+    p.stdin.write(b'print("' + s + b'")\n')
+    p.stdin.close()
+    assert p.stdout.read(len(s)) == s
+
+def test_kill():
+    p = audio.ALSA(tool='python', Fs=32000)
+    p = p.launch(fname='-', stdin=sp.PIPE, stdout=sp.PIPE)
+    p.kill()
+    assert p.wait() == -signal.SIGKILL