Nested Interface Does Not Type Check Function Returns Correctly #26170

calebeno · 2018-08-02T20:17:57Z

TypeScript Version: ^3.1.0-dev.20180802

Search Terms:
Nested Interface
Interface Function
Deep Nested Interface
Deep Object Path

Code

Example 1:

interface TopLevel {
    aProperty: {
        aMethod(): {
            anotherMethod(): string
        }
    };
}

let mockUp: TopLevel = {
    aProperty: {
        aMethod: () => {
            return {
                anotherMethod: () => {
                    return 'string';
                },
                woops: () => {  // This should cause an error, not defined in the interface
                    return 0;
                }
            };
        },
        wrongAgain: () => {  // Causes error as expected
            return 0;
        }
    },
    shouldNotBeHere: 'string'  // This should cause an error, not defined in the interface
};

Example 2:

interface FirstLevel {
    aProperty: SecondLevel;
}

interface SecondLevel {
    aMethod(): ThirdLevel;
}

interface ThirdLevel {
    anotherMethod(): string;
}

let mockUpTwo: FirstLevel = {
    aProperty: {
        aMethod: (): ThirdLevel => {
            return {
                anotherMethod: () => {
                    return 'string';
                },
                woops: () => {  // Causes error as expected
                    return 0;
                }
            };
        },
        wrongAgain: () => {  // Causes error as expected
            return 0;
        }
    },
    shouldNotBeHere: 'string'  // This should cause an error, not defined in the interface
};

Expected behavior:
I was working on some complex nested interfaces with functions and realized that the ts compiler wasn't complaining in certain places when it should have been. These are two examples of the same typed object using a single nested interface and multiple nested interfaces.

Actual behavior:
You can see that there should be three expected errors in both examples but there is only one in the first and two in the second.

Repo
https://github.com/calebeno/ts-nested-interface-issue

Related Issues:

calebeno · 2018-08-02T20:30:26Z

I've seen this one popping up a lot #4742 but I'm not sure if this is the same thing or not as it doesn't contain generics.

RyanCavanaugh · 2018-08-02T20:43:55Z

See #7547

typescript-bot · 2018-12-15T18:00:21Z

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.

RyanCavanaugh added the Duplicate An existing issue was already created label Aug 2, 2018

typescript-bot closed this as completed Dec 15, 2018

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Nested Interface Does Not Type Check Function Returns Correctly #26170

Nested Interface Does Not Type Check Function Returns Correctly #26170

calebeno commented Aug 2, 2018

calebeno commented Aug 2, 2018

RyanCavanaugh commented Aug 2, 2018

typescript-bot commented Dec 15, 2018

Nested Interface Does Not Type Check Function Returns Correctly #26170

Nested Interface Does Not Type Check Function Returns Correctly #26170

Comments

calebeno commented Aug 2, 2018

calebeno commented Aug 2, 2018

RyanCavanaugh commented Aug 2, 2018

typescript-bot commented Dec 15, 2018