StrictPropertyInitialization does not understand calls to helpers

[berickson1]

TypeScript Version: 2.7.0-dev.20180110

Code

export class Test {
    private _foo: string;
    constructor() {
        this._init();
    }

    private _init() {
        this._foo = 'test';
    }
}

https://github.com/berickson1/Playground/blob/master/strictPropertyInitError.ts

Expected behavior:
Code compiles with strict flags on

Actual behavior:
strictPropertyInitError.ts(4,13): error TS2564: Property '_foo' has no initializer and is not definitely assigned in the constructor.

[mhegazy]

The compiler does not analyze all calls from the constructor. for these, use definite assignment operator !. see #20166

[RyanCavanaugh]

See also long discussion of how this would be an expected effect #8476

[berickson1]

I understand that inheritance could make tracking calls from the constructor tricky if public methods were called.
Has there been any thought regarding just tracking private method calls for variable initialization? We've done something similar to reset internal state of classes for unit testing. In this way we could do the following.

export class Test {
    private _foo: string;
    constructor() {
        this._init(); //<- follow this chain
        this.myMethod();//<- don't follow this chain
    }

    private _init(override?: string) {
        this._foo = override || 'test';
    }
    
    public myMethod() {
        this._foo = 'bar'; // This isn't used to track strict property init
    }

    public resetState() {
        this._init('reset');
    }
}

[typescript-bot]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.