Initial Commit

packages/foundation/flow/undo/tests/properties/merge.prop.test.ts

@@ -0,0 +1,51 @@
+import { describe, it } from "@suaveplan/testing/runner";
+import * as fc from "fast-check";
+import { createCommand, executeCommand } from "../../src/command/command.js";
+import { CommandMerger } from "../../src/merge/command-merger.js";
+
+interface Counter {
+    value: number;
+}
+
+describe("property: CommandMerger merge associativity", () => {
+    it("merged command executes to same state as executing individually", {
+        timeout: 30000,
+    }, () => {
+        fc.assert(
+            fc.property(
+                fc.array(fc.integer({ min: 1, max: 10 }), {
+                    minLength: 1,
+                    maxLength: 15,
+                }),
+                (deltas) => {
+                    const commands = deltas.map((d) =>
+                        createCommand<Counter>(
+                            "Inc",
+                            (s) => ({ value: s.value + d }),
+                            (s) => ({ value: s.value - d })
+                        )
+                    );
+
+                    // Execute individually
+                    let individual: Counter = { value: 0 };
+                    for (const cmd of commands) {
+                        individual = executeCommand(individual, cmd);
+                    }
+
+                    // Merge all then execute
+                    const m = new CommandMerger<Counter>({
+                        maxCount: commands.length + 1,
+                    });
+                    for (const cmd of commands) m.add(cmd);
+                    const merged = m.flush();
+                    const mergedResult = merged
+                        ? executeCommand({ value: 0 }, merged)
+                        : { value: 0 };
+
+                    return mergedResult.value === individual.value;
+                }
+            ),
+            { numRuns: 200 }
+        );
+    });
+});