tanhauhau / lazy-jest

Jest util for lazy person like me to generate mass test snapshots with few configurations.

lazy-jest

Jest util for lazy person like me to generate mass test snapshots with few configurations. It only supports function test now

NOTE that please use it wisely, otherwise your snapshot will explode.

Quick start

index.js

export function testFunction(a, b) {
  return a + b;
}

index.test.js

import { testFunction, enumerateArgsTestFunction, configArgs } from 'lazy-jest';
import { targetFunction } from '.';

// custom combinations
testFunction(targetFunction, 
  [
    [1, 2],
    [0, -1],
    [0],
    []
  ], 
  'custom combination test of targetFunction()'
);

// enumerate test
const conf = 
  configArgs()
    .arg('a', [1, 0, -1])
    .arg('b', [-1, 0.9], { invalidCases: [ null ] });
enumerateArgsTestFunction(targetFunction, conf, 'enumerate test for targetFunction()');

How does enumerate test work?

First of all, testing is to verify input samples will always match corresponding output. To know what is the correct output, you need either calculate by yourself, or capture the snapshot of correct output. Which is an owesome feature introduced by jest.

For functions, input is simply a set of arguments. So why not I just provide a list of valid or invalid cases, and let JS to generate all the combinations as test cases and capture snapshot?

To be strict like lab experiments, I choose to test a function in following way (which I called enumerate test):

• If no compulsory args, test function with empty arguments: func()
• If there are compulsory args, test together with invalid case for one of the args, and valid cases for the rest. Like this:
  • func(invalid, valid)
  • func(valid, invalid)
• If there are optional args, test in above way by add in optional args one by one. Like this:
  • func(compulsory_invalid, compulsory_valid, optional_valid)
  • func(compulsory_valid, compulsory_invalid, optional_valid)
  • func(compulsory_valid, compulsory_valid, optional_invalid)
  • func(compulsory_invalid, compulsory_valid, optional_valid, optional_valid)
  • func(compulsory_valid, compulsory_invalid, optional_valid, optional_valid)
  • func(compulsory_valid, compulsory_valid, optional_invalid, optional_valid)
  • func(compulsory_valid, compulsory_valid, optional_valid, optional_invalid)
• And then test all the valid combinations

API

Modules

caseGenerator/configArgs

caseGenerator/configObjectArg

caseGenerator/enumerateArrayCases

caseGenerator/enumerateCases

testFunction

Typedefs

ArgConfig : Object

caseGenerator/configArgs

• caseGenerator/configArgs
  • configArgs(initialConfig) ⇒ exports.Args ⏏
    • .Args
      • new exports.Args(initialConfig)
      • .arg(name, validCases, [opts]) ⇒ this
      • .objectArg(name, propsConfig, [opts]) ⇒ this

---

configArgs(initialConfig) ⇒ exports.Args ⏏

Kind: Exported function

Param	Type
initialConfig	Array.<ArgConfig>

Example

// example ArgConfig for `func(a, b) {}`
configArgs()
.arg('a', [0, 1, 2])
.arg('b', [-1, -2], { optional: true, invalidCases: [0] });

---

configArgs.Args

Class for argument configurations

Kind: static class of configArgs

• .Args
  • new exports.Args(initialConfig)
  • .arg(name, validCases, [opts]) ⇒ this
  • .objectArg(name, propsConfig, [opts]) ⇒ this

---

new exports.Args(initialConfig)

Param	Type
initialConfig	Array.<ArgConfig>

---

args.arg(name, validCases, [opts]) ⇒ this

Add an argument

Kind: instance method of Args

Param	Type	Description
name	string
validCases	Array.<*>	valid test cases for this argument
[opts]	Object.<string, *>	other options

Properties

Name	Type	Description
[opts.optional]	boolean	flag to indicate whether this argument is optional
[opts.invalidCases]	Array.<*>	invalid test cases for thsi argument

---

args.objectArg(name, propsConfig, [opts]) ⇒ this

Add an object type argument

Kind: instance method of Args

Param	Type
name	string
propsConfig	Args | Array.<ArgConfig>
[opts]	Object.<string, *>

Properties

Name	Type
[opts.optional]	boolean

---

caseGenerator/configObjectArg

---

configObjectArg(propsConfig) ⇒ ArgConfig ⏏

A helper to generate object test cases by provided configurations

Kind: Exported function

Param	Type
propsConfig	Args | Array.<ArgConfig>

Example

configObjectArg(
 configArgs()
 .arg('a', [1, 2], { invalidCases: [NaN, 0] })
 .arg('b', ['a'], { invalidCases: ['', 1], optional: true })
);
// Result:
// {
//   validCases: [
//     { a: 1 },
//     { a: 2 },
//     { a: 1, b: a }
//   ],
//   invalidCases: [
//     { a: NaN },
//     { a: 0 },
//     { a: 1, b: '' },
//     { a: 1, b: 1 }
//   ]
// }

---

caseGenerator/enumerateArrayCases

---

enumerateArrayCases ⇒ Array.<(Array.<*>|Object)> ⏏

Kind: Exported constant
See: enumerateCases

Param	Type	Description
argsConfig	Array.<ArgConfig>
invalidArgConfigIndex	number	Index of arg in the config list to have invalid case. If this is not set, it will generate cases that all arguments are valid.

---

caseGenerator/enumerateCases

• caseGenerator/enumerateCases
  • enumerateCases(appendMethod, argsConfig, invalidArgConfigIndex) ⇒ Array.<(Array.<*>|Object)> ⏏
    • ~appendMethod ⇒ Array.<(Array.<*>|Object)>

---

enumerateCases(appendMethod, argsConfig, invalidArgConfigIndex) ⇒ Array.<(Array.<*>|Object)> ⏏

Generate cases by given configuration

Kind: Exported function

Param	Type	Description
appendMethod	appendMethod	This method will receive 2 input: existing case list, case value to extend. And should return extended case list.
argsConfig	Array.<ArgConfig>
invalidArgConfigIndex	number	Index of arg in the config list to have invalid case. If this is not set, it will generate cases that all arguments are valid.

Example

enumerateCases(extendArrayCase, [
 { name: 'a', validCases: [true], invalidCases: [false]},
 { name: 'b', validCases: [1], invalidCases: [2]}
]);
// Result: [[true, 1]]

enumerateCases(extendArrayCase, [
 { name: 'a', validCases: [true], invalidCases: [false]},
 { name: 'b', validCases: [1], invalidCases: [2], optional: true }
]);
// Result: [[true], [true, 1]]

enumerateCases(extendArrayCase, [
 { name: 'a', validCases: [true], invalidCases: [false, 0]},
 { name: 'b', validCases: [1, 2], invalidCases: [3] }
], 0);
// Result: [[false, 1], [0, 1]]

enumerateCases(extendArrayCase, [
 { name: 'a', validCases: [true], invalidCases: [false, 0]},
 { name: 'b', validCases: [1, 2], invalidCases: [3], optional: true }
], 0);
// Result: [[false], [0], [false, 1], [0, 1]]

---

enumerateCases~appendMethod ⇒ Array.<(Array.<*>|Object)>

Kind: inner typedef of enumerateCases

Param	Type	Description
cases	Array.<(Array.<*>|Object)>	generated cases
nextArgCase	*

---

testFunction

• testFunction
  • .testFunction
  • .enumerateArgsTestFunction

---

testFunction.testFunction

Kind: static constant of testFunction

Param	Type
func	function
[argsCases]	Array.<Array.<*>>
[testCaption]	string

Example

testFunction(targetFunction, [
 [1, 2],
 [0, -1],
 [0], 
 []
], 'custom combination test of targetFunction()');

---

testFunction.enumerateArgsTestFunction

Catch snapshot of a function. It will do following tests:

• If no compulsory arguments defined, it will test empty argument case
• Test compulsory arguments first, and add in optional argument test cases one by one
• Test invalid cases by using arguments with one invalid argument, and first valid case for others
• Test all valid combinations of arguments

Kind: static constant of testFunction

Param	Type	Description
func	function	Target function
argsConfig	Args | Array.<ArgConfig>
[testCaption]	string	Test description

Example

const emptyFunc = () => {};
enumerateArgsTestFunction(emptyFunc);

const simpleFunc = (param) => param;
enumerateArgsTestFunction(
  simpleFunc, 
  configArgs().arg('param', [1], { invalidCases: [0] })
]);

const funcHasOptional = (param, opts) => opts || param;
enumerateArgsTestFunction(
 funcHasOpts, 
 configArgs()
   .arg('param', [1], { invalidCases: [0] })
   .arg('opts', [2], { invalidCases: [0], optional: true })
);

const complexFunc = ({ param, opts }) => opts || param;
enumerateArgsTestFunction(
  funcHasOpts, 
  configArgs().objectArg(
    'param',
    configArgs()
      .arg('param', [1], { invalidCases: [0] })
      .arg('opts', [2], { invalidCases: [0], optional: true })
  )
);

---

ArgConfig : Object

Kind: global typedef
Properties

Name	Type
name	string
validCases	Array.<*>
invalidCases	Array.<*>
optional	boolean

---