Add typescript example

examples/typescript/README.md

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+
+# Expect custom message example
+
+## Installation
+
+```
+yarn
+```
+
+## Running test
+
+```
+yarn test
+```

examples/typescript/jest.config.js

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+module.exports = {
+  preset: "ts-jest",
+  testEnvironment: "node",
+  testMatch: ["**/__tests__/**/*.[jt]s?(x)", "**/?(*.)+(spec|test).[tj]s?(x)"],
+  testPathIgnorePatterns: ["/node_modules/"],
+  transform: {
+    "^.+\\.tsx?$": "ts-jest",
+  },
+  setupFilesAfterEnv: ["jest-chain"],
+};

examples/typescript/package.json

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+{
+  "name": "jest-chain-example",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "jest"
+  },
+  "license": "MIT",
+  "dependencies": {},
+  "devDependencies": {
+    "@types/jest": "^29.0.0",
+    "jest": "^29.0.2",
+    "jest-chain": "*",
+    "ts-jest": "^28.0.8",
+    "typescript": "^4.8.2"
+  }
+}

examples/typescript/src/sum.ts

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+const sum = (a: number, b: number): number => a + b;
+
+export default sum;

examples/typescript/test/sum.test.ts

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+import sum from "../src/sum";
+
+describe("Test math", () => {
+  test("Commutative Law of Addition", () => {
+    expect(sum(1, 2)).toBe(sum(2, 1)).toEqual(sum(2, 1));
+  });
+});

examples/typescript/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "es2016",
+    "module": "commonjs",
+    "baseUrl": "./",
+    "esModuleInterop": true,
+    "strict": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "strictBindCallApply": true,
+    "strictPropertyInitialization": true,
+    "noEmit": true
+  },
+
+  "files": ["node_modules/jest-chain/types/index.d.ts"],
+  "include": ["src/**/*", "test/**/*"],
+  "exclude": ["node_modules"]
+}