Add deterministic-tests (#190)

Reviewed-on: https://home.schmelczer.dev/git/git/andras/vault-link/pulls/190
Co-authored-by: Andras Schmelczer <andras@schmelczer.dev>
Co-committed-by: Andras Schmelczer <andras@schmelczer.dev>

frontend/deterministic-tests/src/tests/server-pause-both-edit-same-file.test.ts

@@ -0,0 +1,68 @@
+import type { AssertableState } from "../utils/assertable-state";
+import type { TestDefinition } from "../test-definition";
+
+export const serverPauseBothEditSameFileTest: TestDefinition = {
+    description:
+        "Both clients edit different sections of the same file while the server is paused. After resuming and converging, client 0 makes another edit to verify further updates still work correctly.",
+    clients: 2,
+    steps: [
+        {
+            type: "create",
+            client: 0,
+            path: "shared.md",
+            content: "line 1: original\nline 2: original\nline 3: original"
+        },
+        { type: "enable-sync", client: 0 },
+        { type: "enable-sync", client: 1 },
+        { type: "barrier" },
+
+        { type: "pause-server" },
+
+        {
+            type: "update",
+            client: 0,
+            path: "shared.md",
+            content:
+                "line 1: edited by client 0\nline 2: original\nline 3: original"
+        },
+        {
+            type: "update",
+            client: 1,
+            path: "shared.md",
+            content:
+                "line 1: original\nline 2: original\nline 3: edited by client 1"
+        },
+
+        { type: "resume-server" },
+        { type: "barrier" },
+
+        {
+            type: "assert-consistent",
+            verify: (s: AssertableState): void => {
+                s.assertFileCount(1).assertContains(
+                    "shared.md",
+                    "edited by client 0",
+                    "edited by client 1"
+                );
+            }
+        },
+
+        {
+            type: "update",
+            client: 0,
+            path: "shared.md",
+            content: "post-merge edit from client 0"
+        },
+        { type: "barrier" },
+
+        {
+            type: "assert-consistent",
+            verify: (s: AssertableState): void => {
+                s.assertFileCount(1).assertContains(
+                    "shared.md",
+                    "post-merge edit from client 0"
+                );
+            }
+        }
+    ]
+};