Working on a bug in Microsoft VSCode (Part 2)

Volodymyr Klymenko
Feb 8 · 4 min read

One week ago, I posted an article on how I started working on a bug in Microsoft VSCode. If you haven’t read it yet, I highly recommend reading it:

Quick Recap

The search bar in the extensions part doesn’t save the value if you reload the window.

Steps to reproduce this bug:

  1. Type something in extensions search
  2. Reload window

After reloading the window, the search bar value has gone.

Fix

In the last article, I finished my research, my assumption was that extensions search bar needs to implement some kind of viewletState, which will keep track of its value. I came to this assumption by comparing extensions search bar with the search bar in the Search part of VSCode because the second one keeps the input value even if you reload the window.

After some time, I got a response from Microsoft’s member, and he confirmed that my guess is right. Thus, I could start developing my solution. Even though I knew what I have to do theoretically, it took me a lot of time to implement this bug fix because codebase is large, and I basically couldn’t figure out where exactly and what I should code.

As I found earlier, extensionsViewlet is the component which creates the whole extensions section. When I looked at its code, the following property caught my attention:

private searchBox: SuggestEnabledInput;

After setting some breakpoints and debugging it, I found that this is the input field that I am looking for. When I debugged my breakpoints, I noticed that after I reload the window, and searchBox was rendering, its SuggestEnabledInput constructor is called with these parameters:

constructor(    id: string,    parent: HTMLElement,    suggestionProvider: SuggestResultsProvider,    ariaLabel: string,    resourceHandle: string,    options: SuggestEnabledInputOptions,    @IInstantiationService instantiationService: IInstantiationService,    @IModelService modelService: IModelService,)

I found that options parameter consists of

  • placeholderText?: string;
  • focusContextKey?: IContextKey<boolean>

and the input parameters are assigned to these options.

I tried to add value to the SuggestEnabledInputOptions interface, and pass a “test” string in the extensionsViewlet. Voilà! Each time searchBox is rendered, the default value is “test”:

A small milestone was completed. Now, my task was to keep track of the value and save it inside the state.

Based on the implementation of viewletState in the searchView, I created a searchViewletState in the extensionsViewlet.

I declared a state object at the top of the extensionsViewlet class:

private searchViewletState: object;

Then, I wrote a method for saving the state:

protected saveState(): void {    const value = this.searchBox.getValue();    this.searchViewletState['query.value'] = value;    super.saveState();}

Finally, I used the value from the searchViewletState in the extensionsViewlet create method and passed to the searchBox constructor inside options object (last line):

Here is the result:

As you can see, I type “react” in the searchBar. Then, I reload the window, and the searchBar has a value of “react”!

Conclusion

It was one of the most challenging contributions for me. There are several reasons for that:

  • VSCode has a large codebase, so it was difficult to explore the code and not everything was obvious.
  • I haven’t worked with TypeScript for a while. However, TS actually helped me at some stages of development, and I consider using it in my future React projects!
  • There wasn’t any similar bug fixed in this project before, which is quite seldom for open source projects.

I overcame these challenges, and I was able to fix this issue. I am proud of contributing to the software that millions of developers are using! It’s great to add VSCode to my portfolio of open source contributions.

Volodymyr Klymenko

Written by

Software developer 👨‍💻Open Source contributor 🌎 Seneca ‘19 👨‍🎓