ndb/test: add more test coverage on char iter

nostrdb/Test/NdbTests.swift

@@ -80,12 +80,21 @@ final class NdbTests: XCTestCase {
             return
         }
 
+
+        self.measure {
             var count = 0
             var char_count = 0
+
             for tag in note.tags() {
                 for elem in tag {
                     print("iter_elem \(elem.string())")
-                for _ in elem {
+                    for c in elem {
+                        if char_count == 0 {
+                            let ac = AsciiCharacter(c)
+                            XCTAssertEqual(ac, "p")
+                        } else if char_count == 0 {
+                            XCTAssertEqual(c, 0x6c)
+                        }
                         char_count += 1
                     }
                 }
@@ -98,3 +107,5 @@ final class NdbTests: XCTestCase {
 
     }
 
+}
+