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Writing Unit Tests

Unit testing is an essential part of developing smart contracts on OP_NET. This guide covers the structure of a test file, key components of the OP_NET Unit Test Framework, and best practices for writing effective tests.

Basic Structure of a Test File​

Importing Required Modules and Contracts​

Every test file starts by importing the necessary modules and contracts.

import { Address } from "@btc-vision/transaction";
import {
  Assert,
  Blockchain,
  OP_20,
  opnet,
  OPNetUnit,
} from "@btc-vision/unit-test-framework";

Using the opnet Function for Test Suites​

The opnet function defines the test suite, and each test case is specified within it.

await opnet("Test Suite Name", async (vm: OPNetUnit) => {
  // Define your tests here
});

Defining Test Cases with vm.it​

Each test case is written using vm.it.

await vm.it("should perform a specific action", async () => {
  // Test logic here
  const value = true;
  Assert.expect(value).toEqual(true);
});

Test Lifecycle Hooks​

Setup with vm.beforeEach and vm.afterEach​

Use vm.beforeEach and vm.afterEach to set up and clean up resources for each test.

vm.beforeEach(async () => {
  await Blockchain.init();
});

vm.afterEach(() => {
  Blockchain.dispose();
});

Initializing and Disposing Resources​

For reusable components, initialize them in vm.beforeAll and dispose of them in vm.afterAll.

await vm.beforeAll(async () => {
  await Blockchain.init();
});

vm.afterAll(() => {
  Blockchain.dispose();
});

Asynchronous Testing​

Using async/await in Tests​

All tests support asynchronous operations. Use async/await for clarity and to handle promises.

await vm.it("should execute asynchronously", async () => {
  const result = await Promise.resolve(true);
  Assert.expect(result).toEqual(true);
});

Handling Promises and Callbacks​

For more complex cases, ensure all promises are handled properly.

await Assert.expect(async () => {
  await someAsyncFunction();
}).toNotThrow();

Assertions​

Using the Assert Module​

The Assert module provides methods to validate conditions in your tests.

Common Assertion Methods​

  • toEqual: Compare values for equality.
  • toBe: Validate truthy or falsy values.
  • toThrow: Check for exceptions.
  • toNotThrow: Ensure no exceptions are thrown.
const value = 10;
Assert.expect(value).toEqual(10);

await Assert.expect(async () => {
  const result = await Promise.resolve("success");
  if (!result) throw new Error("Failure");
}).toNotThrow();
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