Add CI tests for unused code

This commit tests in CI for unused functions and exports using ts-prune.

There are two exported functions in ecmascript.ts that are only used by
tests. Because our tests haven't been ported over to TS yet, that usage
is invisible to ts-prune, so I marked both functions with a comment to
disable ts-prune errors until we migrate the test code to TS and we can
remove the `// ts-prune-ignore-next` comments

Author: justingrant

.eslintrc.yml

@@ -36,7 +36,8 @@ rules:
   curly:
     - error
     - multi-line
-  func-call-spacing: error
+  func-call-spacing: off
+  '@typescript-eslint/func-call-spacing': error
   function-call-argument-newline:
     - error
     - consistent

.github/workflows/lint.yml

@@ -11,3 +11,13 @@ jobs:
           node-version: 15.x
       - run: npm ci --no-optional
       - run: npm run lint
+  lint-unused-code: # look for unused functions and unused exports
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: use node.js v16.x
+        uses: actions/setup-node@v1
+        with:
+          node-version: 16.x
+      - run: npm ci --no-optional
+      - run: npm run prune

.github/workflows/test.yml

@@ -28,12 +28,12 @@ jobs:
   test-test262:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-    - name: use node.js v16.x
-      uses: actions/setup-node@v1
-      with:
-        node-version: 16.x
-    - run: npm ci
-    - run: npm run test262
-      env:
-        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+      - uses: actions/checkout@v2
+      - name: use node.js v16.x
+        uses: actions/setup-node@v1
+        with:
+          node-version: 16.x
+      - run: npm ci
+      - run: npm run test262
+        env:
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}

lib/ecmascript.ts

@@ -2322,6 +2322,7 @@ function GetISOPartsFromEpoch(epochNanoseconds) {
   return { epochMilliseconds, year, month, day, hour, minute, second, millisecond, microsecond, nanosecond };
 }
 
+// ts-prune-ignore-next TODO: remove this after tests are converted to TS
 export function GetIANATimeZoneDateTimeParts(epochNanoseconds, id) {
   const { epochMilliseconds, millisecond, microsecond, nanosecond } = GetISOPartsFromEpoch(epochNanoseconds);
   const { year, month, day, hour, minute, second } = GetFormatterParts(id, epochMilliseconds);
@@ -2376,6 +2377,7 @@ export function GetIANATimeZonePreviousTransition(epochNanoseconds, id) {
   return result;
 }
 
+// ts-prune-ignore-next TODO: remove this after tests are converted to TS
 export function GetFormatterParts(timeZone, epochMilliseconds) {
   const formatter = getIntlDateTimeFormatEnUsForTimeZone(timeZone);
   // FIXME: can this use formatToParts instead?