iryna-vys / qa_frontend_intro

QA Frontend Intro

Task

Each of the following helper functions has one or more bugs in their implementation.

• countPages(itemCount, itemsPerPage) from numbers.js accepts a non-negative integer itemCount and a positive integer itemsPerPage and returns the number of pages that itemCount items would require to display, assuming every page can display a maximum of itemsPerPage items. Example: if itemCount === 18 and itemsPerPage === 5, the function should return 4 (as 3 pages can display no more than 15 items, but 4 pages can display as many as 20).

• generateDistinct(nums) from numbers.js accepts an array of numbers as its single parameter and returns an arbitrary number that this array does not include. Example: generateDistinct([2, 1, 5]) === 4 would be fine, as 4 is distinct from 2, 1, and 5.

• generateLarger(nums) from numbers.js accepts a non-empty array of numbers as its single parameter and returns an arbitrary number that is larger than any number in the array. Example: generateLarger([2, 1, 5]) === 8 would be fine, as 8 is larger than 2, 1, and 5.

• generateSmaller(nums) from numbers.js accepts a non-empty array of numbers as its single parameter and returns an arbitrary number that is smaller than any number in the array. Example: generateSmaller([2, 1, 5]) === 0 would be fine, as 0 is smaller than 2, 1, and 5.

• generateRandomInt(from, to) from numbers.js returns a random integer between from and to, inclusive. As this method returns random values, make sure to call it not once but several times with each combination of parameters.

• parseYear(year) from strings.js accepts a string as its only parameter and interprets it as a year: 4-character numeral strings are taken to mean the year itself; 2-character numeral strings are taken to mean a 1900s year; other strings will throw an error. Examples: parseYear('9876') === 9876; parseYear('53') === 1953; parseYear('12345') and parseYear('two thousand') should both throw an error.

• generateRandomTime() from strings.js returns a random time string between '00:00' and '23:59'. It depends on generateRandomInt and might appear to work correctly while that function has an unfixed bug.

• createStampedObject(object) from objects.js accepts an object as its single parameter and returns an object which has all of object’s contents and additionally a field called stamped set to true. The function is not supposed to mutate the initial object.

• stampObject(object) from objects.js accepts an object as its single parameter, mutates it by setting its stamped property to true and returns this object.

• getOwnProperty(object, property) from objects.js returns the own value of the property that the object has. Examples: if object === {hello: 'world', __proto__: {foo: 'bar'}}, then getOwnProperty(object, 'hello') is 'world', while getOwnProperty(object, 'foo') is undefined.

• findItem(items, id) from arrays.js accepts an array of items, each of which should be an object that contains an id field, and and id to search for. It returns the first item with this id or null if no items have such id. Examples: if items === [{name: 'Foo', id: 5}, {name: 'Bar', id: 8}], then findItem(items, 8) is {name: 'Bar', id: 8}, while findItem(items, 6) is null.

• makeArray(...) from arrays.js accepts any number of parameters and transforms them into an array. Example: makeArray(2, 1, 5, 'foo') is [2, 1, 5, 'foo'].

Your task is:

1. Without looking at the actual implementations, create unit tests that would fully cover all use cases for the function you’re testing. Apart from where it is stated otherwise, you don’t need to test how a function will react to an invalid input.
2. Run the tests, make sure that they indeed fail, and verify that it’s a problem in the helpers’ code, not in tests. If some of the helpers pass every test, try to come up with some more edge cases and then repeat this step (make an exception for generateRandomTime which will appear to work correctly until you fix generateRandomInt).
3. Fix the problems in the helpers’ code and run the tests again. Make sure that they now pass, except for generateRandomTime, which should fail.
4. Fix the implementation of generateRandomTime and make sure that all tests now pass.

You can suppress particular ESLint rules in the helpers’ code if you feel it would be impossible to implement them without breaking the rules.

Workflow

• Fork the repository with this task.
• Clone forked repository:

  git clone [email protected]:<user_name>/<task_repository>.git

• Run npm install to install dependencies.
• Work on the task.

Development mode

• Use the npm test command to run the tests that you have created. You would not need to run npm start for this task.
• Follow the simplified JS styleguide.
• Before committing, use npm run lint to check your code for any styling issues.
• Commit and push.
• Create Pull Request from the forked repo to the original one.
• Add the link to the pull request to your Google spreadsheet.

In this task, you will only be working with the src/helpers folder.