Add Nonce spec.

spec/sodium/nonce_spec.cr

@@ -0,0 +1,31 @@
+require "../spec_helper"
+require "../../src/sodium/nonce"
+
+zero = Bytes.new(Sodium::Nonce::NONCE_SIZE)
+one = Bytes.new(Sodium::Nonce::NONCE_SIZE).dup
+one[0] = 1_u8
+
+describe Sodium::Nonce do
+  it "generates a random nonce" do
+    nonce = Sodium::Nonce.random
+    nonce.should_not eq zero
+  end
+
+  it "loads an existing nonce" do
+    nonce = Sodium::Nonce.new one
+    nonce.to_slice.should eq one
+  end
+
+  it "zero nonce with increment" do
+    nonce = Sodium::Nonce.zero
+    nonce.to_slice.should eq zero
+
+    nonce.used?.should be_false
+    nonce.used!
+    nonce.used?.should be_true
+
+    nonce.increment
+    nonce.to_slice.should eq one
+    nonce.used?.should be_false
+  end
+end