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https://github.com/bilby91/jest-change-matchers
Jest change matchers like RSpec
https://github.com/bilby91/jest-change-matchers
javascript jest nodejs rspec typescript
Last synced: 19 days ago
JSON representation
Jest change matchers like RSpec
- Host: GitHub
- URL: https://github.com/bilby91/jest-change-matchers
- Owner: bilby91
- Created: 2018-05-26T02:28:39.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2021-08-22T20:11:30.000Z (about 3 years ago)
- Last Synced: 2024-10-08T03:54:51.190Z (about 1 month ago)
- Topics: javascript, jest, nodejs, rspec, typescript
- Language: TypeScript
- Homepage:
- Size: 46.9 KB
- Stars: 1
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
Awesome Lists containing this project
README
# jest-change-matchers [](https://badge.fury.io/js/jest-change-matchers) [](https://codecov.io/gh/bilby91/jest-change-matchers) [](https://circleci.com/gh/bilby91/jest-change-matchers/tree/master)
Jest matchers to evaluate side effect changes.
## Installation
```shell
yarn add --dev jest-change-matchers
```
## Usage
After installing the packge you will have a few more matchers in your toolbelt. If you are familiar with RSpec, the new matchers
should make you feel like home :).
### toChange
```javascript
describe("toChange", () => {
beforeEach(() => {
sharedState = 0
})
describe(".toChange", () => {
it("passes when there is a change", async () => {
await expect(async () => {
sharedState += 1
}).toChange(async () => {
return sharedState
})
})
it("throws an error when there is no change", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 0
}).toChange(async () => {
return sharedState
})
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
})
describe(".not.toChange", () => {
it("passes when there is no change", async () => {
await expect(async () => {
// no-op
}).not.toChange(async () => {
return sharedState
})
})
it("throws an error when there is a change", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 1
}).not.toChange(async () => {
return sharedState
})
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
})
})
```
### toChangeBy
```javascript
describe("toChangeBy", () => {
beforeEach(() => {
sharedState = 0
})
describe(".toChangeBy", () => {
it("passes with positive changes", async () => {
await expect(async () => {
sharedState += 1
}).toChangeBy(async () => {
return sharedState
}, 1)
})
it("passes with negative changes", async () => {
await expect(async () => {
sharedState -= 1
}).toChangeBy(async () => {
return sharedState
}, -1)
})
it("throws an error when it doesn't change the desired amount", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 2
}).toChangeBy(async () => {
return sharedState
}, 1)
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
})
describe(".not.toChangeBy", () => {
it("passes with positive changes", async () => {
await expect(async () => {
sharedState += 1
}).not.toChangeBy(async () => {
return sharedState
}, -1)
})
it("passes with negative changes", async () => {
await expect(async () => {
sharedState -= 1
}).not.toChangeBy(async () => {
return sharedState
}, 1)
})
it("throws an error when it changes the desired amount", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 2
}).not.toChangeBy(async () => {
return sharedState
}, 2)
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
})
})
```
### toChangeFromTo
```javascript
describe("toChangeFromTo", () => {
beforeEach(() => {
sharedState = 0
})
describe(".toChangeFromTo", () => {
it("passes when it changes from previous and new value", async () => {
await expect(async () => {
sharedState += 1
}).toChangeFromTo(async () => {
return sharedState
}, 0, 1)
})
it("throws an error when it doesn't change from previous value", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 2
}).toChangeFromTo(async () => {
return sharedState
}, 1, 2)
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
it("throws an error when it doesn't change to new value", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 2
}).toChangeFromTo(async () => {
return sharedState
}, 0, 1)
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
})
describe(".not.toChangeFromTo", () => {
it("passes when it doesn't change to previous and new value", async () => {
await expect(async () => {
sharedState += 1
}).not.toChangeFromTo(async () => {
return sharedState
}, 0, 0)
})
it("throws an error when it change to previous and new value", async () => {
const testCase = () => {
return expect(async () => {
sharedState += 2
}).not.toChangeFromTo(async () => {
return sharedState
}, 0, 2)
}
await expect(testCase()).rejects.toThrowErrorMatchingSnapshot()
})
})
})
```
## Contact
- Martín Fernández