Integration test tutorial: Your First Integration Test

[SlamBamActionman]

This PR adds a tutorial for creating a basic integration test.

I am myself a beginner to making tests so I took the opportunity to write as I learned. That of course means I am not fully certain of the accuracy of the text, so do point out inconsistencies. I'd also love to see some additions made to the "Extra credit" section to further explain the core parts of how tests function.

[mqole]

very very cool guide, tysm for your work on it slam! in addition to the notes i left (knowing the bare minimum about tests), some other stuff id like to see covered if time permits:

• when should someone consider making a new integration test? is there any consideration for how much time/memory a new test takes to run / if it would be better to edit an existing test / etc?
• other example keywords that can be used to affect tests (glossary maybe?) - ive seen NonParallelizable, Explicit, etc
• what happens when a test is written poorly and uses up a lot of memory? are there any common pitfalls that should be avoided?

[mqole]

maybe a small note clarifying the differences between integration and unit testing, and if theres ever a situation where it is more appropriate to create a unit test?

could also use [...]about SS14 integration testing and[...] to note that integration tests are a universal concept in software development. (i did not know this until recently as ss14 was my introduction to software dev :p )

[mqole]

term integration test is used 2x, small rephrase suggestion

Suggested change

	**Integration testing** is a useful tool to ensure that changes to one part of the game doesn't unexpectedly cause another part of the game to change too.
	It can catch unintended behavior, bugs and even rare game-crashing errors when used properly!
	This is achieved through **integration tests**, which basically run short simulations of the game and makes sure ingame values match what the test expects.
	The process of **integration testing** ensures that changes to one part of the game don't unexpectedly cause another part of the game to change too.
	It can catch unintended behavior, bugs and even rare game-crashing errors when used properly!
	Integration testing is performed through the use of **integration tests**, which basically run short simulations of the game and make sure the end results of those simulations match what the test expects.

[mqole]

Suggested change

	If you have an integration test that compares order costs to sell values, you'll be able to automatically catch if this change would result in an infinite money loop!
	If you have an integration test that compares order costs to sell values and throws an error if a Cargo order would sell for more money than it costs to buy, you'll be able to automatically catch if this change would result in an infinite money loop!

[mqole]

Suggested change

	Integration tests are ran on all pull requests submitted to the SS14 repository and all tests must pass for a PR to be mergeable.
	Integration tests are automatically run on all pull requests submitted to the SS14 repository, and all tests must pass for a PR to be mergeable.

[mqole]

maybe add a link to src/en/general-development/tips/debugging-tools.md after #629 is merged to clarify how this is done locally

[mqole]

Suggested change

	With our testcase being simply clicking on the huggable entity, we can use of the basic `await Interact();` method to simulate hugging. Since we spawned the `MobHuman` with `SpawnTarget` earlier, all we have to do is run the method!
	With our testcase being simply clicking on the huggable entity, we can make use of the basic `await Interact();` method to simulate hugging. Since we spawned the `MobHuman` with `SpawnTarget` earlier, all we have to do is run the method!

[mqole]

i was initially going to note that you might be able to talk here about how you could go above and beyond and check that they actually spawn with a hand, but then i realised that LastInteractTime wouldnt update if they didnt have a hand lol. might be worth rearticulating that this example test will "check whether a hug is performed" in addition to all the specific technical stuff! (or not, but i imagine someone else might read this and think its a good idea to add a hand test :p )

[mqole]

add that this makes tests run fast (good thing (because they usually take a long time))

[mqole]

'gives access' could be a little clearer. 'gives the test access'?

[mqole]

maybe an example of an integration test which uses PoolManager?

[riccardi48]

From the perspective of someone that doesn't know much about intergration test writing.
I agree that a keyword section would be good to include. A table of the diffrent syntax used in intergration tests would be useful. Like the changes in space-wizards/space-station-14#43875.
An explanation on how the Server and Client are used in intergration tests. On when and how you would test interactions between server and client. I personally don't know the answer to this which is why I think it could be helpful to include.
A section on the thought processes on what to make an intergration test on. A basic checklist of when it is good to make one maybe. The Cargo example you give is good but it is very clear it should be a test, the less obvious times for intergration tests would be good to get across.