lambda-tdd
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Test Framework for AWS Lambda
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# Test Framework for AWS Lambda
[](https://circleci.com/gh/blackflux/lambda-tdd)
[](https://coveralls.io/github/blackflux/lambda-tdd?branch=master)
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[](https://david-dm.org/blackflux/lambda-tdd)
[](https://www.npmjs.com/package/lambda-tdd)
[](https://www.npmjs.com/package/lambda-tdd)
[](https://github.com/semantic-release/semantic-release)
[](https://github.com/blackflux/js-gardener)
Testing Framework for AWS Lambda. Very useful for integration testing as you can examine how your lambda function executes for certain input and specific environment variables. Tries to model the cloud execution as closely as possible.
## What it does
- Tests are defined as JSON files
- Test are dynamically evaluated using [Chai](https://github.com/chaijs/chai)
- Lambda functions are executed using [Lambda-Wrapper](https://github.com/SC5/lambda-wrapper)
- Supports external request mocking using [Nock](https://github.com/node-nock/nock)
- Allows setting of environment variables on a per test granularity
- Freeze execution to specific timestamp with [Timekeeper](https://github.com/vesln/timekeeper)
- Mock randomly generated data, so it does not change between test runs.
- Set lambda timeout (`context.getRemainingTimeInMillis()`)
- Set test timeout
- Specify event input
- Test success and error responses
## Example Projects
Example project using [js-gardener](https://github.com/blackflux/js-gardener) and [lambda-tdd](https://github.com/blackflux/lambda-tdd) can be found [here](https://github.com/blackflux/lambda-example).
## Getting Started
To install run
$ npm install --save-dev lambda-tdd
### Initialize Test Runner and Execute
<!-- eslint-disable import/no-extraneous-dependencies, import/no-unresolved, mocha/no-setup-in-describe -->
```js
import fs from 'smart-fs';
import minimist from 'minimist';
import LambdaTdd from 'lambda-tdd';
LambdaTdd({
cwd: fs.dirname(import.meta.url),
verbose: minimist(process.argv.slice(2)).verbose === true,
timeout: minimist(process.argv.slice(2)).timeout,
nockHeal: minimist(process.argv.slice(2))['nock-heal']
}).execute();
```
You can pass an array of test files to the `execute()` function or a regular expression pattern. By default tests are auto detected. If a pattern is passed in only matching tests are executed.
The example above allows for use of a `--filter=REGEX` parameter to only execute specific tests.
*Note:* If you are running e.g. `npm t` to run your tests you need to specify the filter option with [quadruple dashes](https://github.com/npm/npm/pull/5518). Example:
$ npm t -- --filter=REGEX
### Test File Example
```json
{
"handler": "geoIp",
"envVars": {
"GOOGLE_PROJECT_ID": "123456789"
},
"event": {
"ip": "173.244.44.10"
},
"nock": {
"to": {
"match": "^.*?\"http://ip-api\\.(com|ca):80\".*?$"
}
},
"expect(body)": {
"to.contain": "\"United States\""
},
"timestamp": 1511072994,
"success": true,
"lambdaTimeout": 5000,
"timeout": 5000
}
```
More examples can be found [here](https://github.com/blackflux/lambda-tdd/tree/master/test/sample).
## Test Runner Options
### cwd
Type: `string`<br>
Default: `process.cwd()`
Directory which other defaults are relative to.
### name
Type `string`<br>
Default: `lambda-test`
Name of this test runner for debug purposes.
### verbose
Type `boolean`<br>
Default: `false`
Display console output while running tests. Useful for debugging.
### timeout
Type `integer`<br>
Default: `undefined`
Hard overwrite test timeout for all tests.
### nockHeal
Type `boolean` or `string`<br>
Default: `false`
Set cassette healing flag for underlying [node-tdd](https://github.com/blackflux/node-tdd)
### testHeal
Type `boolean`<br>
Default: `false`
Automatically heals test when possible.
### handlerFile
Type: `string`<br>
Default: `handler.js`
Handler file containing the handler functions (specified in test).
### cassetteFolder
Type: `string`<br>
Default: `__cassettes`
Folder containing nock recordings.
### envVarYml
Type: `string`<br>
Default: `env-vars.yml`
Specify yaml file containing environment variables. To allow overwriting of existing environment variables prefix with `^`. Otherwise an exception is thrown.
Environment variables set by default are `AWS_REGION`, `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` since these always get set by the AWS Lambda environment.
### envVarYmlRecording
Type: `string`<br>
Default: `env-vars.recording.yml`
Similar to envVarYml. Environment variables declared get applied on top of envVarYml iff this is a new test recording.
Great when secrets are needed to record tests, but they should not be committed (recommendation is to git ignore this file).
### testFolder
Type: `string`<br>
Default: ``
Folder containing test files.
### stripHeaders
Type: `boolean`<br>
Default: `false`
Remove rawHeaders from recordings automatically when recording.
### modifiers
Type: `object`<br>
Default: `{}`
Allows definition of custom test file modifiers for `expect` and `event` and for cassette recordings (pipe operator).
Default custom modifiers are: `toBase64`, `toGzip` and `jsonStringify`
### reqHeaderOverwrite
Type: `object`<br>
Default: `{}`
Used to define overwrite values for cassette `reqheaders`.
### callback
Type: `function`<br>
Default: `({ test, output, expect }) => {}`
Called for each successful test. Can be used for additional validation.
## Test File Format
### handler
Type: `string`<br>
*Required*
The handler inside the handler file, i.e. if `handler.js` contained
```javascript
module.exports.returnEvent = (event, context, cb) => cb(null, event);
```
we would set this to `returnEvent`.
### envVars
Type `object`<br>
Default: `{}`
Contains environment variables that are set for this test. Existing environment variables can be overwritten.
### timestamp
Type `unix`<br>
Default: Unfrozen
Set unix timestamp that test executing will see. Time does not progress if this option is set.
### seed
Type `string`<br>
Default: `undefined`
Seed used for randomly generated bytes. This mocks `crypto.randomBytes`.
### reseed
Type `boolean`<br>
Default: `false`
By default every "random function" is seeded once per test run.
When set to `true` every function is re-seeded for every invocation.
Will greatly reduce "randomness" when set to `true`.
### timeout
Type `integer`<br>
Default: Mocha Default Timeout
Set custom timeout in ms for lambda execution. Handy e.g. when recording nock requests.
### event
Type `object`<br>
Default: undefined
Event object that is passed to lambda handler.
Custom actions can be applied by using the pipe character, e.g. `{ "body|JSON.stringify": {...} }` could be used to make input more readable. For more examples see tests.
### lambdaTimeout
Type `integer`<br>
Default: 300000
Set initial lambda timeout in ms. Exposed in lambda function through `context.getRemainingTimeInMillis()`.
The timeout is not enforced, but progresses as expected unless `timestamp` option is used.
### success
Type `boolean`<br>
*Required*
True iff execution is expected to succeed, i.e. no error is passed into callback.
### expect, expect(...)
Type `array`
Default: `[]`
Handle evaluation of response or error (uses success flag). Can define target path, e.g. `expect(some.path)`. Can also apply function with e.g. `expect(body|JSON.parse)`.
More details on dynamic expect handling below.
### response (DEPRECATED)
Type `array`<br>
Default: `[]`
Deprecated. Use "expect" instead.
Dynamic expect logic executed against the response string. More details on dynamic expect handling below.
### error (DEPRECATED)
Type `array`<br>
Default: `[]`
Deprecated. Use "expect" instead.
Dynamic expect logic executed against the error string. More details on dynamic expect handling below.
### body (DEPRECATED)
Type `array`<br>
Default: `[]`
Deprecated. Use "expect" instead.
Dynamic expect logic executed against the response.body string. More details on dynamic expect handling below.
### logs, logs(...)
Type `array`<br>
Default: `[]`
Dynamic expect logic executed against the `console` output. You can use `warn`, `info`, `error` and `log` to access the different log level with e.g. `logs([error])`. More details on dynamic expect handling below.
### nock
Type `array`<br>
Default: `[]`
Dynamic expect logic executed against the nock recording. More details on dynamic expect handling below.
Note that the nock recording must already exist for this check to evaluate correctly.
_Important:_ If you are running into issues with replaying a cassette file you recorded previously, try editing the cassette and stripping information that might change. Also make sure cassette files **never expose secret tokens or passwords**!
### stripHeaders
Type: `boolean`<br>
Default: `?`
Remove rawHeaders from recordings automatically when recording. Defaults depends on value set in runner options.
### allowedUnmatchedRecordings
Type: `array`<br>
Default: `[]`
Can define the recordings that are allowed to be unmatched.
### allowedOutOfOrderRecordings
Type: `array`<br>
Default: `[]`
Can define the recordings that are allowed to be out of order.
## Dynamic Expect Logic
Uses [Chai Assertion Library](http://chaijs.com/api/bdd/) syntax written as json. Lets assume we have an output array `[1, 2]` we want to validate. We can write
```js
import { expect } from 'chai';
expect([1, 2]).to.contain(1);
expect([1, 2]).to.contain(2);
```
as the following json
```json
[{
"to.contain()": 1
}, {
"to": {
"contain()": 2
}
}]
```
Regular expression are supported if the target is a string matching a regular expression.
## Limitations
- Does currently not play nicely with native modules. This is because native modules [can not be invalidated](https://github.com/nodejs/node/issues/5016).
## Contribution / What's next
*Currently nothing planned*