feat(expect): add toBeInstanceOf matcher

[zhiyuang]

implement toBeInstanceOf
related issue: #1825

[Jarred-Sumner]

Can you either add a TODO here to check that the function is a constructor or add a binding for isConstructor?

Checking that the JSType is one of the function types isn't precise enough. Functions can callable and/or constructable. The JSType can be whatever we want, though in most cases it will be one of the 3 that JSType currently checks (just not every case, in theory)

Suggested change

	if (!expected_value.jsType().isFunction()) {
	if (!expected_value.isConstructable()) {

This isConstructor function doesn't exist, but it would be nearly identical to isCallable:

bun/src/bun.js/bindings/bindings.zig

Lines 3528 to 3530 in 4c38798

	pub fn isCallable(this: JSValue, vm: *VM) bool {
	return cppFn("isCallable", .{ this, vm });
	}

bun/src/bun.js/bindings/bindings.cpp

Lines 2425 to 2428 in 4c38798

	bool JSC__JSValue__isCallable(JSC__JSValue JSValue0, JSC__VM* arg1)
	{
	return JSC::JSValue::decode(JSValue0).isCallable();
	}

[Jarred-Sumner]

Thank you for this! One comment

[Jarred-Sumner]

There will be some test failures but don't worry about it - not your fault.

[zhiyuang]

OK，I will check it tmr.

[Jarred-Sumner]

I'll just merge, it's an improvement over status quo and we can clean it up after