feat(lint): support class methods in noFloatingPromises

[kaykdm]

Summary

related: #3187 and #4956
This pull request introduces the support for class methods in noFloatingPromises

Example of invalid code:

calling an async method in the same class

class Test {
  async returnsPromise(): Promise<string> {
    return 'value';
  }
  async someMethod() {
    this.returnsPromise(); // diagnostic here
  }
}

calling an async method from the parent class

class Parent {
  async returnsPromise(): Promise<string> {
    return 'value';
  }
}
class Child extends Parent {
  async someMethod() {
    this.returnsPromise().then(() => { }).finally(() => { }); // diagnostic here
  }
}

property method

class Test {
  returnsPromise: () => Promise<void>
  constructor() {
    this.returnsPromise = () => Promise.resolve();
  }

  async someMethod() {
    this.returnsPromise(); // diagnostic here
  }
}

functions

class Test {
  returnsPromiseFunction = async function (): Promise<string> {
    return 'value';
  }
  returnsPromiseArrowFunction = async (): Promise<string> => {
    return 'value';
  }

  async someMethod() {
    this.returnsPromiseFunction().then(() => { }).finally(() => { }); // diagnostic here
    this.returnsPromiseArrowFunction(); // diagnostic here
  }
}

calling an async method from outside

class Test {
  async returnsPromise(): Promise<string> {
    return 'value';
  }
}
const test = new Test();
test.returnsPromise(); // diagnostic here

Example of valid code:

class Test {
  returnsPromiseProperty: Promise<void>
  constructor() {
    returnsPromiseProperty = new Promise((resolve, reject) => { })
  }
  async returnsPromiseMethod(): Promise<string> {
    return 'value';
  }
  async someMethod() {
    await this.returnsPromiseMethod();
    this.returnsPromiseMethod().catch(() => {})
    await this.returnsPromiseProperty()
  }
}

[codspeed-hq]

CodSpeed Performance Report

Merging #5028 will not alter performance

_{Comparing kaykdm:support-class-method (590769c) with next (7d5ae45)}

Summary

✅ 94 untouched benchmarks

[ematipico]

Thank you @kaykdm, the code looks good, however this checks only class declarations, and doesn't check for class expressions. We should add them

[ematipico]

A class can be initialised as an a declaration or an expression. This means we have to cover expressions too. They have a different node. Check the playground:

class A {}

const b = class {}

[kaykdm]

I have added support for class initialized as an expression.

Also, I have added support for method calls from outside of the Class

class Test {
  async returnsPromise(): Promise<string> {
    return 'value';
  }
}
const test = new Test();
test.returnsPromise(); // diagnostic here

[ematipico]

Thank you. It seels that class expression aren't supported yet:

const b = class {}

Do you plan to do that in this PR?

[kaykdm]

Oh, I see! Now I understand what you mean.
I will do that tomorrow. If you want to merge this PR now, please go ahead, and I will create a separate PR for adding that support.

[kaykdm]

@ematipico

I created a PR! #5098
Support for unnamed class expressions in noFloatingPromises was already implemented when I added support for named class expressions, as shown below. However, the test cases were missing, so I have added test cases for unnamed class expressions.

const b = class B {}

[ematipico]

Thank you @kaykdm

I will merge this PR so you can look at the class expression in a separate PR