Add integration tests for vmdb/loggers.rb

Adds specs for each of the global loggers around the multicast logger
based loggers.

Written in a way where we should be able to swap out what we are using
under the hood for Multicast logger, and the tests should be a litmus
test if we are doing everything correct.  Borrowed a decent number of
tests from lib/vmdb/loggers/multicast_logger_spec.rb since that has the
potential to go away, but we want to test the functionality from that
spec file on all of the existing loggers.

Hopefully most of the specs here are idempotent, but we will see.

spec/lib/vmdb/loggers_spec.rb

@@ -10,6 +10,131 @@ def in_container_env(example)
     ENV['CONTAINER'] = old_env
   end
 
+  shared_examples "has basic logging functionality" do
+    let(:logger1) { subject.loggers.first }
+    let(:logger2) { subject.loggers.to_a.last }
+
+    around do |example|
+      has_old_container_log = true
+      unless subject.loggers.include?($container_log)
+        has_old_container_log = false
+        subject.loggers << $container_log
+      end
+      example.run
+      subject.loggers.delete($container_log) unless has_old_container_log
+    end
+
+    it "responds to #<<" do
+      expect(subject.respond_to?(:<<)).to be true
+    end
+
+    it "responds to #debug" do
+      expect(subject.respond_to?(:debug)).to be true
+    end
+
+    it "responds to #info" do
+      expect(subject.respond_to?(:warn)).to be true
+    end
+
+    it "responds to #error" do
+      expect(subject.respond_to?(:error)).to be true
+    end
+
+    it "responds to #fatal" do
+      expect(subject.respond_to?(:fatal)).to be true
+    end
+
+    it "responds to #unknown" do
+      expect(subject.respond_to?(:unknown)).to be true
+    end
+
+    describe "#datetime_format" do
+      it "works as expected" do
+        expect(subject.datetime_format).to be nil
+      end
+    end
+
+    # Ripped from lib/vmdb/loggers/multicast_logger_spec.rb, but adapted used
+    # in a integration spec fashion to test against all of the configured
+    # loggers, and be idempotent with any of the settings that affect the
+    # levels and number of loggers (always have the $container_log attached to
+    # each of the logs tested here).
+    context "#add" do
+      context "for info logger levels" do
+        around do |example|
+          old_subject_level, subject.level = subject.level, 1
+          example.run
+          subject.level = old_subject_level
+        end
+
+        it "forwards to the other loggers" do
+          expect(logger1).to receive(:add).with(1, nil, "test message")
+          expect(logger2).to receive(:add).with(1, nil, "test message")
+
+          subject.info("test message")
+        end
+      end
+
+      context "for higher logger levels" do
+        around do |example|
+          old_subject_level, subject.level  = subject.level, 1
+          old_logger_1_level, logger1.level = logger1.level, 0
+          example.run
+          subject.level = old_subject_level
+          logger1.level = old_logger_1_level
+        end
+
+        it "only forwards the message if the severity is correct" do
+          [logger1, logger2].each { |l| expect(l).not_to receive(:add) }
+
+          subject.debug("test message")
+        end
+      end
+    end
+
+    context "#level=" do
+      around do |example|
+        old_subject_level, subject.level = subject.level, 0
+        example.run
+        subject.level = old_subject_level
+      end
+
+      it "updates the log level on all backing devices" do
+        expect(logger1.level).to eq(0)
+        expect(logger2.level).to eq(0)
+        expect(subject.level).to eq(0)
+        subject.level = 3
+        expect(logger1.level).to eq(3)
+        expect(logger2.level).to eq(0) # $container_log is always DEBUG
+        expect(subject.level).to eq(3)
+      end
+    end
+
+    context "#<<" do
+      it "forwards to the other loggers" do
+        expect(logger1).to receive(:<<).with("test message")
+        expect(logger2).to receive(:<<).with("test message")
+
+        subject << "test message"
+      end
+    end
+  end
+
+  context "for all multicast loggers" do
+    [
+      $log, $rails_log, $api_log, $miq_ae_logger, $aws_log, $azure_log,
+      $cn_monitoring_log, $datawarehouse_log, $fog_log, $kube_log, $lenovo_log,
+      $nuage_log, $policy_log, $rhevm_log, $scvmm_log, $vcloud_log, $vim_log,
+      $websocket_log
+    ].each do |logger|
+      context "for the #{File.basename(logger.filename)}" do
+        subject { logger }
+
+        include_examples "has basic logging functionality"
+      end
+    end
+  end
+
   describe "#create_multicast_logger (private)" do
     it "defaults the lower level loggers to `DEBUG`" do
       log = described_class.send(:create_multicast_logger, log_file)