[Test Explorer] Cannot see the added test item in the explorer when it's overflow the explorer height

[jdneo]

Does this issue occur when all extensions are disabled?: Yes/No

Version: 1.58.0-insider (user setup)
Commit: 012b146
Date: 2021-06-11T05:14:11.473Z
Electron: 12.0.9
Chrome: 89.0.4389.128
Node.js: 14.16.0
V8: 8.9.255.25-electron.0
OS: Windows_NT x64 10.0.19043

Steps to Reproduce:

1. In the project test-provider-sample add a test child in the run() method of TestCase

if (actual === this.expected) {
   ...
} else {
    const child1 = vscode.test.createTestItem<TestCase>({
        id: `mktests/${this.item.uri!.toString()}/${this.item.label}#1`,
        label: this.item.label,
        uri: this.item.uri!,
    });
    child1.range = this.item.range;
    this.item.addChild(child1);
    const message = vscode.TestMessage.diff(`Expected ${this.item.label}`, String(this.expected), String(actual));
    ...
}

2. Add some more tests in the markdown file and shrink the height of the vs code window
3. Run a markdown file
4. The newly added test case will be overflow and cannot be seen in the test explorer
5. The scroll bar will get updated when the height of vs code is changed

2.mp4

//cc @connor4312 for awareness, but this might be an issue of explorer view

[connor4312]

cc @joaomoreno it seems that adding a child via setChildren doesn't trigger the tree ti check scroll height. Resizing the window by 1px fixes it. Is there guidance on what should happen here?

[joaomoreno]

Resizing the window by 1px fixes it.

This usually means we haven't called tree.layout() every time we should've.

This looks very suspicious: https://github.com/microsoft/vscode/blob/274cbd8e0541b02a71ddcd3a7f043e9291a47a69/src/vs/workbench/contrib/testing/browser/testingExplorerView.ts/#L432-L437

We should be forwarding those dimensions down to the tree here instead: https://github.com/microsoft/vscode/blob/274cbd8e0541b02a71ddcd3a7f043e9291a47a69/src/vs/workbench/contrib/testing/browser/testingExplorerView.ts/#L205-L212

[connor4312]

Ah, nevermind, I found the issue 🙂 It's this message. Initially it's hidden, but then when we show it later we don't adjust the height of the tree to compensate for it.

[jdneo]

/verified