Simplify test code a bit, use Request::new() to simplfy constructing requests

tests/common_io_test.rs

@@ -5,10 +5,9 @@ use std::io::Cursor;
 fn it_reads_strings() {
     let buffer = [0x0, 0x3, b'F', b'o', b'o'];
 
-    assert_eq!(
-        read_string(&mut buffer.as_ref()).unwrap(),
-        "Foo".to_string()
-    );
+    let result = read_string(&mut buffer.as_ref()).unwrap();
+
+    assert_eq!(result, "Foo");
 }
 
 #[test]
@@ -17,8 +16,5 @@ fn it_writes_strings() {
 
     write_string(&mut buffer, "Foo").unwrap();
 
-    // Should have written exactly 5 bytes
-    assert_eq!(buffer.get_ref().len(), 5usize);
-
-    assert_eq!(&buffer.get_ref()[0..5], [0x0, 0x3, b'F', b'o', b'o']);
+    assert_eq!(buffer.into_inner(), [0x0, 0x3, b'F', b'o', b'o']);
 }