Dynamically generate test cases with Jest

As long as you know which cases you want to test up-front (for example, you're not trying to generate them after a network request) you can use Jest to batch out multiple cases at once.

The syntax looks like this

test.each([])("test name", () => {})

Single argument per test

If you use the wildcard %s in your test name, it will inject the first string in your test case. The following test spec will generate five different tests.

test.each([
  'FULL_TIME',
  'PART_TIME',
  'SELF_EMPLOYED',
  'UNEMPLOYED',
  'RETIRED',
])('can set employment type to %s', (type) => {
 
  // Test content here
}),

test("can set employment type to FULL_TIME", () => {
  const type = "FULL_TIME"
 
  // Test content here
})
 
test("can set employment type to PART_TIME", () => {
  const type = "PART_TIME"
 
  // Test content here
})
 
test("can set employment type to SELF_EMPLOYED", () => {
  const type = "SELF_EMPLOYED"
 
  // Test content here
})
 
test("can set employment type to UNEMPLOYED", () => {
  const type = "UNEMPLOYED"
 
  // Test content here
})
 
test("can set employment type to RETIRED", () => {
  const type = "RETIRED"
 
  // Test content here
})

Multiple arguments per test

Each item in the array can itself be an array of arguments.

In the test name, you can use %s multiple times in order to print out the argument.

test.each([
  ['FULL_TIME', 'FULL_TIME'],
  ['FULL_TIME', 'PART_TIME'],
  ['FULL_TIME', 'SELF_EMPLOYED'],
  ['FULL_TIME', 'UNEMPLOYED'],
  ['FULL_TIME', 'RETIRED'],
  ['PART_TIME', 'FULL_TIME'],
  ['PART_TIME', 'PART_TIME'],
  ['PART_TIME', 'SELF_EMPLOYED'],
  ['PART_TIME', 'UNEMPLOYED'],
  ['PART_TIME', 'RETIRED'],
  ['SELF_EMPLOYED', 'FULL_TIME'],
  ['SELF_EMPLOYED', 'PART_TIME'],
  ['SELF_EMPLOYED', 'SELF_EMPLOYED'],
  ['SELF_EMPLOYED', 'UNEMPLOYED'],
  ['SELF_EMPLOYED', 'RETIRED'],
  ['UNEMPLOYED', 'FULL_TIME'],
  ['UNEMPLOYED', 'PART_TIME'],
  ['UNEMPLOYED', 'SELF_EMPLOYED'],
  ['UNEMPLOYED', 'UNEMPLOYED'],
  ['UNEMPLOYED', 'RETIRED'],
  ['RETIRED', 'FULL_TIME'],
  ['RETIRED', 'PART_TIME'],
  ['RETIRED', 'SELF_EMPLOYED'],
  ['RETIRED', 'UNEMPLOYED'],
  ['RETIRED', 'RETIRED'],
])('can set employment type from %s to %s', ([ firstType, secondType ]) => {
 
  // Test content here
}),

test("can set employment type from FULL_TIME to FULL_TIME", () => {
  const firstType = "FULL_TIME"
  const secondType = "FULL_TIME"
 
  // Test content here
})
 
test("can set employment type from FULL_TIME to PART_TIME", () => {
  const firstType = "FULL_TIME"
  const secondType = "PART_TIME"
 
  // Test content here
})
 
test("can set employment type from FULL_TIME to SELF_EMPLOYED", () => {
  const firstType = "FULL_TIME"
  const secondType = "SELF_EMPLOYED"
 
  // Test content here
})
 
// …and so on 22 more times