added unique constraint assertion tools

tests/unique.test.ts

@@ -0,0 +1,50 @@
+import { describe, it, expect } from 'vitest';
+import { z } from 'zod';
+import { assertUniqueKeys } from "../pkg/unique";
+
+describe("assert unique", () => {
+    it("should assert unique keys in a homogenous array", () => {
+        const data = [
+            { id: 1, name: "John" },
+            { id: 2, name: "Doe" },
+            { id: 3, name: "Jane" },
+        ];
+        const validator = z.object({
+            id: z.number(),
+            name: z.string(),
+        });
+
+        expect(
+            () => assertUniqueKeys(data, validator, "id")
+        ).not.toThrow();
+    })
+
+    it("should reject arrays violating unique key constraints", () => {
+        const data = [
+            { id: 1, name: "John" },
+            { id: 1, name: "Doe" },
+            { id: 1, name: "Jane" },
+        ];
+        const validator = z.object({
+            id: z.number(),
+            name: z.string(),
+        });
+
+        expect(
+            () => assertUniqueKeys(data, validator, "id")
+        ).toThrowError("Encountered duplicate values in unique field");
+    })
+
+    it("should only allow record types", () => {
+        const data = [
+            2, 3, 4, 5, "foo", "bar", true
+        ];
+
+        const validator = z.union([z.number(), z.string(), z.boolean()]);
+
+        expect(
+            // @ts-expect-error
+            () => assertUniqueKeys(data, validator)
+        ).toThrow();
+    })
+})