Support for skipping only when the exercise allows it

src/output.ts

@@ -31,6 +31,8 @@ type ExerciseConfig = {
     'flag.tests.task-per-describe': boolean
     'flag.tests.may-run-long': boolean
     'flag.tests.includes-optional': boolean
+    'flag.tests.jest'?: boolean
+    'flag.tests.tstyche'?: boolean
   }
 }
 
@@ -66,11 +68,9 @@ export class Output {
       this.results.status =
         aggregatedResults.numRuntimeErrorTestSuites === 0 &&
         aggregatedResults.numFailedTestSuites === 0 &&
-        // Pending tests are skipped tests. test.skip tests are fine in our
-        // reporter and should not be forced to have ran here. So the next
-        // line is commented out.
+        // Pending tests are skipped tests. test.skip tests are fine if the
+        // exercise reports that there are optional tests.
         //
-        // aggregatedResults.numPendingTests === 0 &&
         aggregatedResults.numFailedTests === 0
           ? 'pass'
           : 'fail'
@@ -88,6 +88,24 @@ export class Output {
             'an issue if the problem persists.'
         )
       }
+
+      if (
+        this.results.status === 'pass' &&
+        (aggregatedResults.numPendingTests !== 0 ||
+          aggregatedResults.numPendingTestSuites !== 0)
+      ) {
+        if (
+          !this.configFlag('flag.tests.includes-optional') &&
+          this.config?.custom
+        ) {
+          this.results.status = 'fail'
+          this.error(
+            'Expected to see 0 skipped tests and 0 skipped test suites. ' +
+              'None of the tests in this exercise are optional. The skipped ' +
+              'tests will not show up, but were found during the last run.'
+          )
+        }
+      }
     }
 
     const parsedSources: Record<