tests: add tests for build-dir

tests/apps/python/sub-app/Procfile

@@ -0,0 +1,2 @@
+web: python3 web.py
+release: python3 release.py

tests/apps/python/sub-app/release.py

@@ -0,0 +1,10 @@
+#!/usr/bin/env python
+import os
+
+
+def main():
+    print("SECRET_KEYS: {0}".format(os.getenv('SECRET_KEY')))
+
+
+if __name__ == '__main__':
+    main()

tests/apps/python/sub-app/web.py

@@ -0,0 +1,23 @@
+import http.server
+import json
+import os
+
+
+class GetHandler(http.server.BaseHTTPRequestHandler):
+    def do_GET(self):
+        self.send_response(200)
+        self.send_header("Content-Type", "text/plain; charset=utf-8")
+        self.end_headers()
+
+        if self.path == '/':
+            self.wfile.write("python/http.server".encode("utf-8"))
+        else:
+            data = json.dumps(dict(os.environ), sort_keys=True, indent=4)
+            self.wfile.write(data.encode("utf-8"))
+
+
+if __name__ == "__main__":
+    port = int(os.getenv("PORT", 5000))
+    server = http.server.HTTPServer(("0.0.0.0", port), GetHandler)
+    print("Listening on port {0}".format(port))
+    server.serve_forever()