Let's you swap between source and test files easily. Currenly only supports javascript and related naming conventions.
Run the Peek or Open to the side commands to see the corresponding test or source file.
[
{
"key": "cmd+t",
"command": "extension.peekTestFileToTheSide"
},
{
"key": "cmd+shift+t",
"command": "extension.peekTestFile"
}
]