Filter a snippet by filename or extension, like *.spec.ts and *.spec.js?

Question

I want to add a couple of snippets to use when creating javascript/typescript unit tests but I do not find any way to set the global scope of the snippet to *.spec.ts or *.spec.js

Is this possible? In the documentation they say that the scope is bases on the language identifier but I just see a way to add another extensions to each language there.

Answer 1

You can do this for snippets. In your keybindings.json:

{
    "key": "shift+alt+2",
    "command": "editor.action.insertSnippet",

    "when": "resourceFilename =~ /\\.spec\\.[tj]s$/",

    // with the snippet text directly in the keybinding   

    "args": {
      "snippet": "console.log($1)$0"
    }
},

---

or this keybinding:

{
  "key": "shift+alt+2",
  "command": "editor.action.insertSnippet",
  "when": "resourceFilename =~ /\\.spec\\.[tj]s$/",
  "args": {
    "name": "unit tests"
  }
}

with this snippet in a snippet file:

"unit tests": {
    //  "prefix": "",  // not used here

    "body": [
      "console.log($1)$0",
    ],

The key to limiting the scope of the snippet is this when clause:

"when": "resourceFilename =~ /\\.spec\\.[tj]s$/",

which as a regular expression would look for a filename ending with .spec.ts or .spec.js (note that you need double escapes before the period). So use the resourceFileName and construct a regex that looks at the end of it.

Now your chosen keybinding will work in a *.spec.ts or *.spec.js file only.

See a when clause acting as a regular expression, in keybindings documentation:

key-value when clause operator

There is a key-value pair operator for when clauses. The expression key =~ value treats the right hand side as a regular expression to match against the left hand side. For example, to contribute context menu items for all Docker files, one could use:

"when": "resourceFilename =~ /docker/"

I found this thanks to this issue: resourceExtname with two dots not working