Lesson 7- Explain Unit test for constructor

[VeerniVishwanath]

I'm having a hard time understanding how the assert part passes the test in the following code
at video time

describe( "constructor", async () => {
        it( "sets the aggregator address correctly", async () => {
            const response = await fundMe.priceFeed()
            console.log(`Response: ${response} `)
            console.log(mockV3Aggregator);
            assert.equal(response, mockV3Aggregator.address)
        })
    })

Question:
The response returns an address while the mockV3Aggregator returns an [object] how come assert.equal returns true and passes the test? Shouldn't assert.equal check if the given values are equal are not?

[othaime-en]

Hey @VeerniVishwanath you are right, response returns an address while mockV3Aggregator is an object. However, mockV3Aggregator.address which is used in the assert is not an object, it is also an address.
In your code above, I'm seeing you are logging both response and mockV3Aggregator to the terminal. To test my theory, try logging out mockV3Aggregator.address instead of just mockV3Aggregator and you'll finally see that the two are equal.
Use console.log(mockV3Aggregator.address);

[VeerniVishwanath]

I'm such an idiot.. I totally ignored the . address part .. Thanks man

[othaime-en]

Welcome :)

[astr0-g]

Yes, you are right, assert.equal checks if the given values are equal are not.

For your concerns. MockV3Aggregator is the mock contract you deployed, so MockV3Aggregator.address will return its deployed address.

This test is to ensure the main contract is using the right MockV3Aggregator contract by identify its contract address.

[VeerniVishwanath]

Yes I just realised it .. Thank you man 😅

[ghost]

While we're on this topic, I have a doubt that I want someone to clear for me:

Since priceFeed is an instance to the AggregatorV3Interface contract, why does await fundMe.priceFeed() in the test script returns an address? What does "priceFeed()" do?

Someone please clear it for me. I feel like ripping my head off.

[ghost]

NVM, figured it out!

For someone else struggling with this: apparently, Solidity creates a getter function for all public variables by default.

So for priceFeed variable, Solidity creates a getter function that returns the address of the AggregatorV3Interface contract upon calling await fundMe.priceFeed().