The custom user agent is now appended to the default user agent

If no custom user agent is provided, the default user agent is used.

    dnsimple-ruby/1.0

If a custom user agent is provided, the final user agent is the combination of the custom user agent
prepended by the default user agent.

    dnsimple-ruby/1.0 customAgentFlag

lib/dnsimple/client.rb

@@ -169,18 +169,19 @@ def request(method, path, data = nil, options = {})
     private
 
     def request_options(custom_options = {})
-      options = base_options
-      add_auth_options!(options)
-      add_proxy_options!(options)
-      Extra.deep_merge!(options, custom_options)
+      base_options.tap do |options|
+        Extra.deep_merge!(options, custom_options)
+        Extra.deep_merge!(options, headers: { "User-Agent" => format_user_agent })
+        add_auth_options!(options)
+        add_proxy_options!(options)
+      end
     end
 
     def base_options
       {
           format:   :json,
           headers:  {
-              'Accept' => 'application/json',
-              'User-Agent' => user_agent,
+              "Accept" => "application/json",
           },
       }
     end
@@ -201,6 +202,25 @@ def add_auth_options!(options)
       end
     end
 
+    # Builds the final user agent to use for HTTP requests.
+    #
+    # If no custom user agent is provided, the default user agent is used.
+    #
+    #     dnsimple-ruby/1.0
+    #
+    # If a custom user agent is provided, the final user agent is the combination
+    # of the custom user agent prepended by the default user agent.
+    #
+    #     dnsimple-ruby/1.0 customAgentFlag
+    #
+    def format_user_agent
+      if user_agent.to_s.empty?
+        Dnsimple::Default::USER_AGENT
+      else
+        "#{Dnsimple::Default::USER_AGENT} #{user_agent}"
+      end
+    end
+
     def content_type(headers)
       headers["Content-Type"] || "application/json"
     end

lib/dnsimple/default.rb

@@ -61,10 +61,10 @@ def domain_api_token
         ENV['DNSIMPLE_API_DOMAIN_TOKEN']
       end
 
-      # Default User-Agent header string from ENV or {USER_AGENT}
+      # Default User-Agent header string from ENV
       # @return [String]
       def user_agent
-        ENV['DNSIMPLE_USER_AGENT'] || USER_AGENT
+        ENV['DNSIMPLE_USER_AGENT']
       end
 
       # Default Proxy address:port from ENV

spec/dnsimple/client_spec.rb

@@ -118,7 +118,7 @@
 
       expect(WebMock).to have_requested(:get, "https://api.dnsimple.com/foo").
           with(basic_auth: %w(user pass),
-               headers: { 'Accept' => 'application/json', 'User-Agent' => "dnsimple-ruby/#{Dnsimple::VERSION}" })
+               headers: { 'Accept' => 'application/json', 'User-Agent' => Dnsimple::Default::USER_AGENT })
     end
 
     it "delegates to HTTParty" do
@@ -129,7 +129,7 @@
               "#{subject.base_url}foo",
               format: :json,
               basic_auth: { username: "user", password: "pass" },
-              headers: { 'Accept' => 'application/json', 'User-Agent' => "dnsimple-ruby/#{Dnsimple::VERSION}" }
+              headers: { 'Accept' => 'application/json', 'User-Agent' => Dnsimple::Default::USER_AGENT }
           ).
           and_return(double('response', code: 200))
 
@@ -144,7 +144,7 @@
               body: JSON.dump(something: "else"),
               query: { foo: "bar" },
               basic_auth: { username: "user", password: "pass" },
-              headers: { 'Accept' => 'application/json', 'Content-Type' => 'application/json', 'User-Agent' => "dnsimple-ruby/#{Dnsimple::VERSION}", "Custom" => "Header" }
+              headers: { 'Accept' => 'application/json', 'Content-Type' => 'application/json', 'User-Agent' => Dnsimple::Default::USER_AGENT, "Custom" => "Header" }
           ).
           and_return(double('response', code: 200))
 
@@ -158,7 +158,7 @@
               format: :json,
               body: { something: "else" },
               basic_auth: { username: "user", password: "pass" },
-              headers: { 'Accept' => 'application/json', 'Content-Type' => 'application/x-www-form-urlencoded', 'User-Agent' => "dnsimple-ruby/#{Dnsimple::VERSION}" }
+              headers: { 'Accept' => 'application/json', 'Content-Type' => 'application/x-www-form-urlencoded', 'User-Agent' => Dnsimple::Default::USER_AGENT }
           ).
           and_return(double('response', code: 200))
 
@@ -172,25 +172,25 @@
               format: :json,
               http_proxyaddr: "example-proxy.com",
               http_proxyport: "4321",
-              headers: { 'Accept' => 'application/json', 'User-Agent' => "dnsimple-ruby/#{Dnsimple::VERSION}" }
+              headers: { 'Accept' => 'application/json', 'User-Agent' => Dnsimple::Default::USER_AGENT }
           ).
           and_return(double('response', code: 200))
 
       subject = described_class.new(proxy: "example-proxy.com:4321")
       subject.request(:get, "test", nil, {})
     end
 
-    it "default options can be overriden" do
+    it "supports custom user agent" do
       expect(HTTParty).to receive(:get).
           with(
               "#{subject.base_url}test",
               format: :json,
-              headers: { "Accept" => "application/json", "User-Agent" => "dnsimple-custom-integration" }
+              headers: hash_including("User-Agent" => "#{Dnsimple::Default::USER_AGENT} customAgent")
           ).
           and_return(double("response", code: 200))
 
-      subject = described_class.new
-      subject.request(:get, "test", nil, headers: { "User-Agent" => "dnsimple-custom-integration" })
+      subject = described_class.new(user_agent: "customAgent")
+      subject.request(:get, "test", nil)
     end
   end