Week 6

Question 1

What is a ‘unit’?

Answer 1

A single function or method.
One test per module/class per production module/class, which tests the public interface of the production class.

Question 2

What do opponents of unit tests say?

Answer 2

They complain about having to test all methods in order to achieve high test coverage.
Test only public interfaces, do not test trivial code.
(getters/setters).

Question 3

What ratio of production code to unit tests should we have? (in lines of code)

Answer 3

1:3

Question 4

What does the Arrange-Act-Assert pattern divide tests into?

Answer 4

Arrange section
Act section
Assert section
XD

Question 5

What is the arrange section?

Answer 5

You bring the system under test and its dependencies to a desired state (e.g. fake a database with 3 records in it (mock or stub))

Question 6

What is the act section?

Answer 6

Call functions/methods on the system under test, passing the prepared dependencies, and capturing the output value

Question 7

The assert section

Answer 7

Verify the outcome. May be represented by the return value, final state of the SUT and its collaborators, or the methods the SUT called on those collaborators.

Question 8

What are the phases of Test Driven Development?

Answer 8

Red- write an automated test for some behaviour
Green - write just enough code to pass the test
Refactor - change the code so that it becomes better.

Can lead to poor structure and hacky code.

Question 9

Why has version control turned into build management?

Answer 9

Version control used to be a safe place for source code, now it allows for collaboration, build management etc.

Question 10

What is build management?

Answer 10

Driven by version control, providing:
1. change histories
2. branching and merging
3. traceability

Question 11

What are change histories in build management?

Answer 11

Makes it possible to quickly and reliably get any version of a file.

Question 12

What is branching and merging in build management?

Answer 12

Makes it possible for developers to work independently, and combine their work together, warning of any conflicts. You work on a branch off of the main trunk, and merge them back later.

Question 13

What is traceability in build management?

Answer 13

Annotating each change with a short message describing the purpose of the change.

Question 14

What are the 7 essential practices of continuous integration?

Answer 14

1. do not check in on a broken build
2. always run commit tests locally
3. wait for commit tests to pass
4. never go home on a broken build
5. always be prepared to revert
6. do not comment out failing tests
7. take responsibility for breakages

Question 15

What is ‘do not check in on a broken build’?

Answer 15

There is no point checking in further changes, triggering new builds, and compounding the failure on a broken build.

Question 16

What is ‘always run commit tests locally’?

Answer 16

Only commit once a local build is successful.

Question 17

What is ‘wait for commit tests to pass’?

Answer 17

Check in at least an hour before the end of the working day, or first thing next morning. Don’t go home on a broken build.

Question 18

What is ‘always be prepared to revert’?

Answer 18

If a problem with a commit cannot be fixed quickly, revert it.

Question 19

What is ‘do not comment out failing tests’?

Answer 19

This is the start of a slippery slope to low quality. Do not comment out failing tests. Fix them.

Question 20

What is ‘take responsibility for breakages’?

Answer 20

If you break it, you fix it, now.

Question 21

What are build indicators?

Answer 21

Green indicates when a build is good, red indicates when a build is bad. They are hooked up to a build management.

Question 22

What are the two branching models?

Answer 22

Feature based development
Trunk based development

Question 23

What is feature based development?

Answer 23

A branch is made for each feature being developed
Merging branches is delayed until the feature is finished, possibly weeks later
Can cause inconsistencies over long periods of time, resolve conflicts.

Question 24

What is trunk based development?

Answer 24

In trunk-based development, a branch is again created for each feature being developed.
Merging branches is done daily, with feature flags used to hide incomplete work.

Question 25

What are the two repo organisation types?

Answer 25

Monorepo
Multirepo

Question 26

What is monorepo?

Answer 26

One common repo organisation, monorepo, has one giant repo for all microservices - any check in triggers the production of multiple microservices
Avoid this in the early stages of a project.