jest-test-utils

Utility functions for use in tests using jest.

Installation

npm install --save-dev jest-test-utils

Usage

Setup jest

Add this to your jest config to extend jest expect with SQL statement matchers:

{
    "setupFilesAfterEnv": ["node_modules/jest-test-utils/dist/jest/sqlStatementMatchers.js"]
}

If you want to mock the i18next module, you can also add this to your jest config:

{
    "setupFilesAfterEnv": ["node_modules/jest-test-utils/dist/jest/mockI18next.js"]
}

After this mock is applied i18next.t() no longer returns the translation of the provided key but instead returns the key itself, or an object with the translation key and provided options. This way you can use the same function to test that the correct translation values were provided.

SQL statement matchers

function	description
toSelectFromTable	Verify that the sql statement selects from the specified table.
toSelectDistinctFromTable	Verify that the sql statement selects distinct values from the specified table.
toReplaceIntoTable	Verify that the sql statement replaces into the specified table.
toInsertIntoTable	Verify that the sql statement inserts into the specified table. In the optional options object you can specify an OR action.
toUpdateTable	Verify that the sql statement updates the specified table.
toDeleteFromTable	Verify that the sql statement deletes from the specified table.
toJoinTable	Verify that the sql statement joins another table.
toSelectAllPropertiesOf	Verify that the sql statement selects all the columns of the specified DTO object.
toSetColumn	Verify that the sql statement sets the value of the specified column.
toInsertValues	Verify that the sql statement inserts values into a table.
toUseColumnsInCorrectOrder	Verify that the sql statement uses all specified columns in the correct order.
toUseWhereClause	Verify that the sql statement uses the specified where clause.
toOrderBy	Verify that the sql statement orders by the specified column.
toGroupBy	Verify that the sql statement groups the result by the specified column.

manyOf

This function can be used to create multiple (exactly three) test objects.

interface MyObject {
    id: string,
    value: number,
}

// Function to create an instance of MyObject with random values
function createMyObject (template?: Partial<MyObject>): MyObject {
    return {
        id: getRandomId(),
        value: getRandomValue(),
        ...template,
    };
}

// In a test:
const myObjects = manyOf(createMyObject);

// Or setting fix values
const myObject = manyOf(() => createMyObject({ value: 42 }));

// Or setting values by index
const myObject = manyOf(createMyObject, index => ({ id: `${index}` }));