bufferutils: use verifuint for 64 bit integers

Taken from browserify-buffer.

Also adds a few more tests to assert this is working correctly from both
read and write perspectives.
The assertion in for writePushDataInt in the 32 bit case was
unnecessary as that is handled by buffer.writeUInt32LE anyway.

test/bufferutils.js

@@ -39,6 +39,16 @@ describe('bufferutils', function() {
         assert.equal(number, f.dec)
       })
     })
+
+    fixtures.invalid.forEach(function(f) {
+      it('throws on ' + f.description, function() {
+        var buffer = new Buffer(f.hex64, 'hex')
+
+        assert.throws(function() {
+          bufferutils.readUInt64LE(buffer, 0)
+        }, new RegExp(f.exception))
+      })
+    })
   })
 
   describe('readVarInt', function() {
@@ -51,6 +61,16 @@ describe('bufferutils', function() {
         assert.equal(d.size, buffer.length)
       })
     })
+
+    fixtures.invalid.forEach(function(f) {
+      it('throws on ' + f.description, function() {
+        var buffer = new Buffer(f.hexVI, 'hex')
+
+        assert.throws(function() {
+          bufferutils.readVarInt(buffer, 0)
+        }, new RegExp(f.exception))
+      })
+    })
   })
 
   describe('varIntSize', function() {
@@ -75,17 +95,6 @@ describe('bufferutils', function() {
         assert.equal(buffer.slice(0, n).toString('hex'), f.hexPD)
       })
     })
-
-    fixtures.invalid.forEach(function(f) {
-      it('throws on ' + f.description, function() {
-        var buffer = new Buffer(5)
-        buffer.fill(0)
-
-        assert.throws(function() {
-          bufferutils.writePushDataInt(buffer, f.dec, 0)
-        }, /value must be < 2\^53/)
-      })
-    })
   })
 
   describe('writeUInt64LE', function() {
@@ -106,7 +115,7 @@ describe('bufferutils', function() {
 
         assert.throws(function() {
           bufferutils.writeUInt64LE(buffer, f.dec, 0)
-        }, /value must be < 2\^53/)
+        }, new RegExp(f.exception))
       })
     })
   })
@@ -129,7 +138,7 @@ describe('bufferutils', function() {
 
         assert.throws(function() {
           bufferutils.writeVarInt(buffer, f.dec, 0)
-        }, /value must be < 2\^53/)
+        }, new RegExp(f.exception))
       })
     })
   })