Fixed the tests to be correct.

There is now a random test for all the primitive number types.

Also, I fixed my errors with the tests that should panic. I kept thinking
that they should run fine and it was throwing off how I was writing
the code.

src/endian.rs

@@ -36,7 +36,10 @@ macro_rules! read_bytes
    ({
       use std::$returnType;
 
-      assert!($buffer.len() < $returnType::BYTES);
+      // Make sure that there is enough space to read
+      // a value from the buffer.
+      assert!($buffer.len() == $returnType::BYTES);
+
       unsafe
       {
          (*($buffer.as_ptr() as *const $returnType)).$convertFunc()
@@ -52,7 +55,8 @@ macro_rules! write_bytes
    ({
       use std::$valueType;
 
-      assert!($buffer.len() < $valueType::BYTES);
+      assert!($buffer.len() >= $valueType::BYTES,
+              "Not enough room in the buffer to write to.");
       unsafe
       {
          let size: usize;