write simple e2e test

tests/e2e.py

@@ -1 +1,21 @@
-print("Hello, world!")
+import tempfile
+import os
+import subprocess
+
+with tempfile.TemporaryDirectory() as tmpdir:
+    srcdir = os.path.join(tmpdir, 'src')
+    os.mkdir(srcdir)
+    with open(os.path.join(srcdir, 'test.txt'), 'w') as f:
+        f.write('Hello')
+    mountdir = os.path.join(tmpdir, 'mount')
+    os.mkdir(mountdir)
+    overlaydir = os.path.join(tmpdir, 'overlay')
+    os.mkdir(mountdir)
+    subprocess.run(["./mayakashi.exe", "create", "-i", srcdir, "-o", os.path.join(tmpdir, 'hello'), "-j", "2"]).check_returncode()
+    mounter = subprocess.Popen(["./marmounter.exe", "./hello.mar", "mountpoint=" + mountdir, "overlaydir=" + overlaydir])
+    try:
+        with open(os.path.join(mountdir, 'test.txt'), 'r') as f:
+            assert f.read() == 'Hello'
+    finally:
+        mounter.terminate()
+