Detect server start/stop more reliably.

This is useful, especially in testing, since your test
hosts might not reliabliy start the server within two
seconds, so we do a definite check before progressing.

By the same token, after `kill $server_pid` wait for
the pid to be gone from the process list.

Since now the script can end prematurely, I also added
a cleanup function to make sure the temporary certs are
removed in any case.

n.b. this could also be done with the use of `trap 'fn'
ERR` but that felt like a bit too much magic for this
short a script.

tests/test_datasette_https_server.sh

@@ -4,6 +4,10 @@
 python -m trustme
 # This creates server.pem, server.key, client.pem
 
+cleanup () {
+    rm server.pem server.key client.pem
+}
+
 # Start the server in the background
 datasette --memory \
     --ssl-keyfile=server.key \
@@ -13,21 +17,48 @@ datasette --memory \
 # Store the background process ID in a variable
 server_pid=$!
 
+test_url='https://localhost:8152/_memory.json'
+
 # Wait for the server to start
-sleep 2
+
+# h/t https://github.com/pouchdb/pouchdb/blob/25db22fb0ff025b8d2c698da30c6c409066baa0c/bin/run-test.sh#L102-L113
+waiting=0
+until $(curl --output /dev/null --silent --insecure --head --fail --max-time 2 $test_url); do
+    if [ $waiting -eq 4 ]; then
+        echo "$test_url can not be reached, server failed to start"
+        cleanup
+        exit 1
+    fi
+    let waiting=waiting+1
+    sleep 1
+done
 
 # Make a test request using curl
-curl -f --cacert client.pem 'https://localhost:8152/_memory.json'
+curl -f --cacert client.pem $test_url
 
 # Save curl's exit code (-f option causes it to return one on HTTP errors)
 curl_exit_code=$?
 
 # Shut down the server
 kill $server_pid
-sleep 1
+waiting=0
+#         show all pids
+#         |       find just the $server_pid
+#         |       |                  don’t match on the previous grep
+#         |       |                  |            we don’t need the output
+#         |       |                  |            |
+until ( ! ps ax | grep $server_pid | grep -v grep > /dev/null ); do
+    if [ $waiting -eq 4 ]; then
+        echo "$server_pid does still exist, server failed to stop"
+        cleanup
+        exit 1
+    fi
+    let waiting=waiting+1
+    sleep 1
+done
 
 # Clean up the certificates
-rm server.pem server.key client.pem
+cleanup
 
 echo $curl_exit_code
 exit $curl_exit_code