diff --git a/src/shared/bigint-util.test.ts b/src/shared/bigint-util.test.ts
new file mode 100644
index 0000000..24f5ae8
--- /dev/null
+++ b/src/shared/bigint-util.test.ts
@@ -0,0 +1,66 @@
+import { bigIntReplacer, convertBigIntToString } from "./bigint-util"
+
+const BIG_INT_VALUE = BigInt(10 ** 20)
+const BIG_INT_STRING_VALUE = "100000000000000000000"
+
+describe("bigIntReplacer", () => {
+	it("should convert bigint to string", () => {
+		const sut = {
+			key: BIG_INT_VALUE,
+			nestedKey: {
+				key: BIG_INT_VALUE,
+			},
+		}
+		const result = JSON.stringify(sut, bigIntReplacer)
+		expect(result).toBe(`{"key":"${BIG_INT_STRING_VALUE}","nestedKey":{"key":"${BIG_INT_STRING_VALUE}"}}`)
+	})
+
+	it("should return value as is if not a bigint", () => {
+		const sut = {
+			key: 100,
+		}
+		const result = JSON.stringify(sut, bigIntReplacer)
+		expect(result).toBe('{"key":100}')
+	})
+})
+
+describe("convertBigIntToString", () => {
+	it("should convert bigint to string", () => {
+		const result = convertBigIntToString(BIG_INT_VALUE)
+		expect(result).toBe(BIG_INT_STRING_VALUE)
+	})
+
+	it("should convert bigint in array to string", () => {
+		const result = convertBigIntToString([BIG_INT_VALUE, 123])
+		expect(result).toEqual([BIG_INT_STRING_VALUE, 123])
+	})
+
+	it("should convert bigint in object to string", () => {
+		const result = convertBigIntToString({ key: BIG_INT_VALUE, anotherKey: 123 })
+		expect(result).toEqual({ key: BIG_INT_STRING_VALUE, anotherKey: 123 })
+	})
+
+	it("should handle nested structures", () => {
+		const data = {
+			key: BIG_INT_VALUE,
+			nested: {
+				anotherKey: BIG_INT_VALUE,
+				array: [BIG_INT_VALUE, 123],
+			},
+		}
+		const expected = {
+			key: BIG_INT_STRING_VALUE,
+			nested: {
+				anotherKey: BIG_INT_STRING_VALUE,
+				array: [BIG_INT_STRING_VALUE, 123],
+			},
+		}
+		const result = convertBigIntToString(data)
+		expect(result).toEqual(expected)
+	})
+
+	it("should return non-bigint values as is", () => {
+		const result = convertBigIntToString(123)
+		expect(result).toBe(123)
+	})
+})
diff --git a/vitest.workspace.ts b/vitest.workspace.ts
index d6ed7cf..5f4ee37 100644
--- a/vitest.workspace.ts
+++ b/vitest.workspace.ts
@@ -77,4 +77,27 @@ export default defineWorkspace([
 			},
 		},
 	},
+	{
+		test: {
+			globals: true,
+			exclude: ["**/node_modules/**", "**/dist/**", "**/docs/**", "**/public/**", "**/test-apps/**"],
+			environment: "node",
+			root: "./src/shared",
+			name: "react-router-devtools/shared",
+			// @ts-expect-error
+			coverage: {
+				provider: "v8",
+				include: ["src/**/*"],
+				reporter: ["text", "json-summary", "json", "html"],
+				reportOnFailure: true,
+				all: false,
+				thresholds: {
+					statements: 70,
+					branches: 75,
+					functions: 70,
+					lines: 70,
+				},
+			},
+		},
+	},
 ])