add missing tests for CaseInsensitiveString

Author: ianbotsf

runtime/runtime-core/common/test/aws/smithy/kotlin/runtime/collections/CaseInsensitiveStringTest.kt

@@ -0,0 +1,27 @@
+package aws.smithy.kotlin.runtime.collections
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+class CaseInsensitiveStringTest {
+    @Test
+    fun testEquality() {
+        val left = "Banana".toInsensitive()
+        val right = "baNAna".toInsensitive()
+        assertEquals(left, right)
+        assertNotEquals<Any>("Banana", left)
+        assertNotEquals<Any>("baNAna", right)
+
+        val nonMatching = "apple".toInsensitive()
+        assertNotEquals(nonMatching, left)
+        assertNotEquals(nonMatching, right)
+    }
+
+    @Test
+    fun testProperties() {
+        val s = "BANANA".toInsensitive()
+        assertEquals("BANANA", s.original)
+        assertEquals("banana", s.normalized)
+    }
+}