Add convenience methods for inspecting vapid key

lib/webpush/vapid_key.rb

@@ -49,6 +49,15 @@ def group
       curve.group
     end
 
+    def to_h
+      { public_key: public_key, private_key: private_key }
+    end
+    alias to_hash to_h
+
+    def inspect
+      "#<#{self.class}:#{object_id.to_s(16)} #{to_h.map { |k, v| ":#{k}=#{v}" }.join(" ")}>"
+    end
+
     private
 
     def to_big_num(key)

spec/webpush/vapid_key_spec.rb

@@ -19,6 +19,22 @@
     expect(Base64.urlsafe_decode64(key.private_key).bytesize).to eq(32)
   end
 
+  it "pretty prints encoded keys" do
+    key = Webpush::VapidKey.new
+    printed = key.inspect
+
+    expect(printed).to match(/public_key=#{key.public_key}/)
+    expect(printed).to match(/private_key=#{key.private_key}/)
+  end
+
+  it "returns hash of public and private keys" do
+    key = Webpush::VapidKey.new
+    hash = key.to_h
+
+    expect(hash[:public_key]).to eq(key.public_key)
+    expect(hash[:private_key]).to eq(key.private_key)
+  end
+
   describe "self.from_keys" do
     it "returns an encoded public key" do
       key = Webpush::VapidKey.from_keys(vapid_public_key, vapid_private_key)