add test cases

test.js

@@ -0,0 +1,45 @@
+var assert = require('assert');
+var log    = console.log;
+var rbytes = require('./index');
+var buf;
+var octets = [0xa8, 0x75, 0xfe, 0xae, 0xc6, 0x7f, 0x00, 0x00, 0xa8, 0x75];
+
+log("random bytes");
+buf = rbytes.randomBytes(12);
+assert.ok(Buffer.isBuffer(buf));
+assert.equal(buf.length, 12);
+
+log("buffer to hex");
+buf = Buffer(octets);
+assert.equal(buf.toHex(), "a875feaec67f0000a875");
+
+log("write hex to buffer");
+buf = Buffer(10);
+assert.equal(buf.writeHex("a875feaec67f0000a875"), 10);
+assert.equal(buf.length, 10);
+for (var i=0; i<10; i++) {
+  assert.equal(buf[i], octets[i]);
+}
+
+log("add leading 0");
+buf = Buffer(1)
+assert.equal(buf.writeHex("f"), 1);
+assert.equal(buf.toHex(), "0f");
+
+log("too small");
+buf = Buffer(1);
+assert.throws(function() { buf.writeHex("ffff") },
+  Error, "Buffer too small");
+
+buf = Buffer(10);
+assert.throws(function() { buf.writeHex("a875feaec67f0000a8751") },
+  Error, "Buffer too small");
+
+log("invalid hex");
+buf = Buffer(10);
+assert.throws(function() { buf.writeHex("gfhf") },
+  TypeError, "Invalid hex string");
+
+buf = Buffer(1);
+assert.throws(function() { buf.writeHex("g") },
+  TypeError, "Invalid hex string");