types: add Satoshi

test/types.js

@@ -46,4 +46,19 @@ describe('types', function () {
       }, /Expected Buffer\(Length: 32\), got Buffer\(Length: 20\)/)
     })
   })
+
+  describe('Satoshi', function () {
+    [
+      { value: -1, result: false },
+      { value: 0, result: true },
+      { value: 1, result: true },
+      { value: 20999999 * 1e8, result: true },
+      { value: 21000000 * 1e8, result: true },
+      { value: 21000001 * 1e8, result: false }
+    ].forEach(function (f) {
+      it('returns ' + f.result + ' for valid for ' + f.value, function () {
+        assert.strictEqual(types.Satoshi(f.value), f.result)
+      })
+    })
+  })
 })