TypeScript: support testing

[huonw]

Is your feature request related to a problem? Please describe.

We have typescript_test and tsx_test (and so on) targets, but the test goal doesn't find them.

Describe the solution you'd like

Running pants test :: should run typescript tests, somehow.

Notes:

• these may interact with javascript tests
• tools like @babel/preset-typescript (https://jestjs.io/blog/2019/01/25/jest-24-refreshing-polished-typescript-friendly#typescript-support) and https://www.npmjs.com/package/ts-jest allow .ts files to be fed into jest directly, i.e. npx jest will run .ts tests.

Demo using ts-jest:

cd $(mktemp -d)

cat > package.json <<'EOF'
{
  "name": "demo",
  "version": "0.0.1",
  "scripts": {
    "test": "npx jest"
  },
  "dependencies": {
    "@types/jest": "29.5.14",
    "jest": "29.7.0",
    "ts-jest": "29.3.0"
  },
  "jest": {
    "testMatch": ["<rootDir>/**/*.test.{js,ts}"],
    "transform": {
      "^.+\\.tsx?$": "ts-jest"
    }
  }
}
EOF

cat > typescript.test.ts <<EOF
test("typescript", () => {});
EOF


# setup the lockfile
npm install

# OKAY: running tests outside of pants runs TS tests
npm test
#  PASS  ./typescript.test.ts


# Now try Pants:
cat > pants.toml <<EOF
[GLOBAL]
pants_version = "2.26.0a0"

backend_packages.add = [
  "pants.backend.experimental.javascript",
  "pants.backend.experimental.typescript",
]

[nodejs]
package_manager = "npm"
EOF

cat > BUILD <<EOF
package_json(name="root", dependencies=[], scripts=[node_test_script()])

typescript_tests(name="ts_tests")
EOF

# Currently runs nothing:
pants test ::

Describe alternatives you've considered

None yet.

Additional context

[lucacavallaro]

Hello my org uses vitest instead of jest, and it has native support for .ts files. Is there a way to support this scenario? I am available to work on this issue, if needed.