eslint-plugin-jest/lib/rules/__tests__/no-large-snapshots.test.js

Eslint rules for Jest

'use strict';

const _require = require('eslint'),
      RuleTester = _require.RuleTester;

const rule = require('../no-large-snapshots');

const noLargeSnapshots = rule.create;
const ruleTester = new RuleTester({
  parserOptions: {
    ecmaVersion: 2015
  }
});
ruleTester.run('no-large-snapshots', rule, {
  valid: [{
    filename: 'mock.js',
    code: `expect(something).toMatchInlineSnapshot(\`\n${'line\n'.repeat(2)}\`);`
  }, {
    filename: 'mock.js',
    code: `expect(something).toThrowErrorMatchingInlineSnapshot(\`\n${'line\n'.repeat(2)}\`);`
  }],
  invalid: [{
    filename: 'mock.js',
    code: `expect(something).toMatchInlineSnapshot(\`\n${'line\n'.repeat(50)}\`);`,
    errors: [{
      messageId: 'tooLongSnapshots',
      data: {
        lineLimit: 50,
        lineCount: 51
      }
    }]
  }, {
    filename: 'mock.js',
    code: `expect(something).toThrowErrorMatchingInlineSnapshot(\`\n${'line\n'.repeat(50)}\`);`,
    errors: [{
      messageId: 'tooLongSnapshots',
      data: {
        lineLimit: 50,
        lineCount: 51
      }
    }]
  }]
}); // was not able to use https://eslint.org/docs/developer-guide/nodejs-api#ruletester for these because there is no way to configure RuleTester to run non .js files

describe('no-large-snapshots', () => {
  it('should return an empty object for non snapshot files', () => {
    const mockContext = {
      getFilename: () => 'mock-component.jsx',
      options: []
    };
    const result = noLargeSnapshots(mockContext);
    expect(result).toEqual({});
  });
  it('should return an object with an ExpressionStatement function for snapshot files', () => {
    const mockContext = {
      getFilename: () => 'mock-component.jsx.snap',
      options: []
    };
    const result = noLargeSnapshots(mockContext);
    expect(result).toMatchObject({
      ExpressionStatement: expect.any(Function)
    });
  });
  describe('ExpressionStatement function', () => {
    it('should report if node has more than 50 lines of code and no sizeThreshold option is passed', () => {
      const mockReport = jest.fn();
      const mockContext = {
        getFilename: () => 'mock-component.jsx.snap',
        options: [],
        report: mockReport
      };
      const mockNode = {
        loc: {
          start: {
            line: 1
          },
          end: {
            line: 53
          }
        }
      };
      noLargeSnapshots(mockContext).ExpressionStatement(mockNode);
      expect(mockReport).toHaveBeenCalledTimes(1);
      expect(mockReport.mock.calls[0]).toMatchSnapshot();
    });
    it('should report if node has more lines of code than number given in sizeThreshold option', () => {
      const mockReport = jest.fn();
      const mockContext = {
        getFilename: () => 'mock-component.jsx.snap',
        options: [{
          maxSize: 70
        }],
        report: mockReport
      };
      const mockNode = {
        loc: {
          start: {
            line: 20
          },
          end: {
            line: 103
          }
        }
      };
      noLargeSnapshots(mockContext).ExpressionStatement(mockNode);
      expect(mockReport).toHaveBeenCalledTimes(1);
      expect(mockReport.mock.calls[0]).toMatchSnapshot();
    });
    it('should report if maxSize is zero', () => {
      const mockReport = jest.fn();
      const mockContext = {
        getFilename: () => 'mock-component.jsx.snap',
        options: [{
          maxSize: 0
        }],
        report: mockReport
      };
      const mockNode = {
        loc: {
          start: {
            line: 1
          },
          end: {
            line: 2
          }
        }
      };
      noLargeSnapshots(mockContext).ExpressionStatement(mockNode);
      expect(mockReport).toHaveBeenCalledTimes(1);
      expect(mockReport.mock.calls[0]).toMatchSnapshot();
    });
    it('should not report if node has fewer lines of code than limit', () => {
      const mockReport = jest.fn();
      const mockContext = {
        getFilename: () => 'mock-component.jsx.snap',
        options: [],
        report: mockReport
      };
      const mockNode = {
        loc: {
          start: {
            line: 1
          },
          end: {
            line: 18
          }
        }
      };
      noLargeSnapshots(mockContext).ExpressionStatement(mockNode);
      expect(mockReport).not.toHaveBeenCalled();
    });
  });
});