add UT for wave.py

tests/test_wave.py

@@ -0,0 +1,23 @@
+from amodem import wave
+import subprocess as sp
+import signal
+
+
+def test_launch():
+    p = wave.launch('cat', stdin=sp.PIPE)
+    p.stdin.close()
+    assert p.wait() == 0
+
+    p = wave.launch('bash', stdin=sp.PIPE)
+    p.stdin.write(b'exit 42')
+    p.stdin.close()
+    assert p.wait() == 42
+
+    p = wave.launch('cat', stdin=sp.PIPE, stdout=sp.PIPE)
+    s = b'Hello World!'
+    p.stdin.write(s)
+    p.stdin.flush()
+    assert p.stdout.read(len(s)) == s
+
+    p.kill()
+    assert p.wait() == -signal.SIGKILL