[VAULT-34754] Refactor Test_ConcurrentCompileInternedRegexps to also exercise MustCompileInterned; fixed a typo in the godoc comment

Author: kubawi

regexp/regexp_test.go

@@ -138,12 +138,13 @@ func TestCleanupCorrectKind(t *testing.T) {
 	l.Unlock()
 }
 
-// Test_ConcurrentInternedRegexps tests that multiple goroutines can compile
+// Test_ConcurrentCompileInternedRegexps tests that multiple goroutines can compile
 // and use interned regular expressions concurrently without issues.
 // We spin up a number of goroutines that compile the same interned regexp
 // and hold on to it for a second. If there are any issues with concurrent access,
 // this test should trip the race detector.
 func Test_ConcurrentCompileInternedRegexps(t *testing.T) {
+	t.Parallel()
 	var wg sync.WaitGroup
 	pattern := ".*"
 
@@ -154,10 +155,12 @@ func Test_ConcurrentCompileInternedRegexps(t *testing.T) {
 			defer wg.Done()
 			exp, err := CompileInterned(pattern)
 			require.NoError(t, err)
+			exp2 := MustCompileInterned(pattern)
 			// We want to hold a reference to the compiled regexp to ensure it is not
 			// garbage collected before other goroutines are spun up.
 			time.Sleep(1 * time.Second)
 			exp.Match([]byte("test"))
+			exp2.Match([]byte("test"))
 		}()
 	}
 	wg.Wait()