integration-tests: Cleanup, add parallelism test

integration-tests/parallel/default.nix

@@ -0,0 +1,27 @@
+let
+  tools = import ../tools.nix {};
+in tools.makeTest {
+  name = "colmena-parallel";
+
+  bundle = ./.;
+
+  testScript = ''
+    deployer.succeed("cd /tmp/bundle &&" \
+        "${tools.colmenaExec} apply push -v --eval-node-limit 4 --on @target")
+
+    logs = deployer.succeed("cd /tmp/bundle &&" \
+        "run-copy-stderr ${tools.colmenaExec} apply switch -v --eval-node-limit 4 --parallel 4 --on @target")
+
+    for node in [alpha, beta, gamma]:
+        node.succeed("grep SUCCESS /etc/deployment")
+
+    with subtest("Check that activation is correctly parallelized"):
+        timestamps = list(map(lambda l: int(l.strip().split("---")[1]) / 1000000,
+            filter(lambda l: "Activation triggered" in l, logs.split("\n"))))
+
+        delay = max(timestamps) - min(timestamps)
+        deployer.log(f"Time between activations: {delay}ms")
+
+        assert delay < 2000
+  '';
+}