Lesson 9 : Does the contract return the variable name along with value?

[jksgfsdfd]

I have implemented a slightly different version of the contract and test.
How is the return value of checkUpKeep extracted in this line?

const { upkeepNeeded } = await lotteryContract.checkUpkeep("0x");
assert.equal(upkeepNeeded, false);

If I change the name of the variable to anything other than "upkeepNeeded" , the test fails and the variable is undefined. How does this occur? How is my test able to know the name of the variable used inside my contract?

[alymurtazamemon]

@ronmaa Then you should write the same name here instead of upkeepNeeded.

This is called destructuring in JavaScript, you can read about this topic for more information.

[jksgfsdfd]

To destructure in this manner, shouldn't the returned object from checkUpkeep be like this?
{ upkeepNeeded : false }
So the names of return variables are also stored inside the bytecode?

[alymurtazamemon]

@ronmaa in the contract we have a solidity return type.