我想用Jest测试两个功能。但是,我无法将测试覆盖率提高到100%,因为我不知道如何将String.prototype.trimLeft
模拟为undefined
。我该怎么办?
function trimLeft (str: string): string {
if (String.prototype.trimLeft) {
return str.trimLeft()
} else {
return str.replace(/^[\s\uFEFF\xA0]+/, '')
}
return str
// else something's wrong
}
function trimRight (str: string, type: string): string {
if (String.prototype.trimRight) {
return str.trimRight()
} else {
return str.replace(/[\s\uFEFF\xA0]+$/, '')
}
return str
}
export { trimLeft, trimRight }
答案 0 :(得分:1)
首先,在这两种方法中,最后一条语句return str
不可访问。修复它们之后。这是单元测试解决方案:
index.ts
:
function trimLeft(str: string): string {
if (String.prototype.trimLeft) {
return str.trimLeft();
} else {
return str.replace(/^[\s\uFEFF\xA0]+/, '');
}
}
function trimRight(str: string): string {
if (String.prototype.trimRight) {
return str.trimRight();
} else {
return str.replace(/[\s\uFEFF\xA0]+$/, '');
}
}
export { trimLeft, trimRight };
index.spec.ts
:
import { trimLeft, trimRight } from './';
describe('59430114', () => {
describe('#trimLeft', () => {
it('t1', () => {
expect(trimLeft(' jestjs')).toBe('jestjs');
});
it('t2', () => {
Object.defineProperty(String.prototype, 'trimLeft', { value: undefined });
expect(trimLeft(' jestjs')).toBe('jestjs');
});
});
describe('#trimRight', () => {
it('t1', () => {
expect(trimRight('jestjs ')).toBe('jestjs');
});
it('t2', () => {
Object.defineProperty(String.prototype, 'trimRight', { value: undefined });
expect(trimRight('jestjs ')).toBe('jestjs');
});
});
});
覆盖率100%的单元测试结果:
PASS src/stackoverflow/59430114/index.spec.ts (8.386s)
59430114
#trimLeft
✓ t1 (4ms)
✓ t2 (1ms)
#trimRight
✓ t1 (1ms)
✓ t2 (1ms)
----------|----------|----------|----------|----------|-------------------|
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files | 100 | 100 | 100 | 100 | |
index.ts | 100 | 100 | 100 | 100 | |
----------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests: 4 passed, 4 total
Snapshots: 0 total
Time: 10.085s
源代码:https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/59430114