cypress-commands-db.js

module.exports = function() {
  Cypress.Commands.add('sqlServer', (query) => {
    if(!query) {
      throw new Error('Query must be set');
    }

    cy.task('sqlServer:execute', query).then(response => {
      let result = [];

      const flatten = r => Array.isArray(r) && r.length === 1 ? flatten(r[0]) : r;

      if(response) {
        for (let i in response) {
          result[i] = [];
          for (let c in response[i]) {
            result[i][c] = response[i][c].value;
          }
        }
        result = flatten(result);
      } else {
        result = response;
      }

      return result;
    });
  });
}

cypress-plugins-db.js

const Tedious = require('tedious');

module.exports = (dbConfig) => {
    return {
      'sqlServer:execute': (sql) => {
        const connection = new Tedious.Connection(dbConfig);
        return new Promise((res, rej) => {
          connection.on('connect', err => {
            if (err) {
              rej(err);
            }

            const request = new Tedious.Request(sql, function(err, rowCount, rows) {
              return err ? rej(err) : res(rows);
            });

            connection.execSql(request);
          });
        });
      }
    }
  };