[CLOUD-319] Make mixlib-log an optional dependency

This change makes mixlib-log an optional dependency. When it's available
in the LOAD_PATH it will be used by default, otherwise, all logging will
will be forwarded to a null logger that does nothing. This is useful for
cases where small utilities can consume mixlib-authentication and not
have to pull in additional gems.

Signed-off-by: Ryan Cragun <me@ryan.ec>

2 files changed, 56 insertions, 2 deletions

diff --git a/spec/mixlib/authentication/mixlib_authentication_spec.rb b/spec/mixlib/authentication/mixlib_authentication_spec.rb
index d0e8071..221e803 100644
--- a/spec/mixlib/authentication/mixlib_authentication_spec.rb
+++ b/spec/mixlib/authentication/mixlib_authentication_spec.rb
@@ -63,8 +63,7 @@ class MockFile
 end
 
 # Uncomment this to get some more info from the methods we're testing.
-#Mixlib::Authentication::Log.logger = Logger.new(STDERR)
-#Mixlib::Authentication::Log.level :debug
+#Mixlib::Authentication.logger.level = :debug
 
 describe "Mixlib::Authentication::SignedHeaderAuth" do
 
diff --git a/spec/mixlib/authentication/mixlib_log_missing_spec.rb b/spec/mixlib/authentication/mixlib_log_missing_spec.rb
new file mode 100644
index 0000000..4b12b12
--- /dev/null
+++ b/spec/mixlib/authentication/mixlib_log_missing_spec.rb
@@ -0,0 +1,55 @@
+describe "Mixlib::Authentication::Log" do
+  before do
+    Mixlib::Authentication.send(:remove_const, "DEFAULT_SERVER_API_VERSION")
+    Mixlib::Authentication.send(:remove_const, "Log")
+  end
+
+  context "without mixlib-log" do
+    before do
+      @mixlib_path = $LOAD_PATH.find { |p| p.match("mixlib-log") }
+      $LOAD_PATH.reject! { |p| p.match("mixlib-log") }
+
+      load "mixlib/authentication.rb"
+    end
+
+    after do
+      $LOAD_PATH.unshift(@mixlib_path)
+    end
+
+    it "uses MixlibLogMissing" do
+      expect(Mixlib::Authentication::Log.singleton_class.included_modules)
+        .to include(Mixlib::Authentication::NullLogger)
+    end
+
+    it "default log level is :error" do
+      expect(Mixlib::Authentication::Log.level).to eq(:error)
+    end
+
+    %w{debug info warn error fatal}.each do |level|
+      it "logs at level #{level}" do
+        expect(Mixlib::Authentication::Log).to receive(level).with("foo")
+
+        Mixlib::Authentication.logger.send(level, "foo")
+      end
+    end
+  end
+
+  context "with mixlib-log" do
+    before do
+      load "mixlib/authentication.rb"
+    end
+
+    it "uses Mixlib::Log" do
+      expect(Mixlib::Authentication::Log.singleton_class.included_modules)
+        .to include(Mixlib::Log)
+    end
+
+    %w{debug info warn error fatal}.each do |level|
+      it "forward #{level} to mixlib-log" do
+        expect(Mixlib::Authentication::Log.logger).to receive(level).with("foo")
+
+        Mixlib::Authentication.logger.send(level, "foo")
+      end
+    end
+  end
+end