Fix some utils, spacing, func naming, test inputs, etc.

internal/testutil/stringutil.go

@@ -0,0 +1,14 @@
+// Copyright 2024 the Pinniped contributors. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package testutil
+
+import "strings"
+
+func SplitByNewline(lineToSplit string) []string {
+	if len(lineToSplit) == 0 {
+		return nil
+	}
+
+	return strings.Split(strings.TrimSpace(lineToSplit), "\n")
+}