TECH-4787: add test for inline context and no progname; add support f…

…or all 3: progname, context, message block

lib/contextual_logger.rb

@@ -68,19 +68,29 @@ def current_context_for_thread
       Context::Handler.current_context
     end
 
-    # In methods below, we assume that presence of context means new code that is aware of
-    # ContextualLogger...and that that code never uses progname.
+    # In the methods generated below, we assume that presence of context means new code that is
+    # aware of ContextualLogger...and that that code never uses progname.
     # This is important because we only get 2 args total passed to add(), in order to be
-    # compatible with classic implementations like in the plain Logger
-    # and ActiveSupport::Logger.broadcast.
+    # compatible with classic implementations like in the plain Logger and
+    # ActiveSupport::Logger.broadcast.
+
+    # Note that we can't yield before add because `add` might skip it based on log_level. And we can't check
+    # log_level here because we might be running in ActiveSupport::Logging.broadcast which has multiple
+    # loggers, each with their own log_level.
 
     LOG_LEVEL_NAMES_TO_SEVERITY.each do |method_name, log_level|
       class_eval(<<~EOS, __FILE__, __LINE__ + 1)
-        def #{method_name}(arg = nil, context = nil, &block)
-          if context
-            add(#{log_level}, arg, context, &block)
-          else
+        def #{method_name}(arg = nil, **context, &block)
+          if context.empty?
             add(#{log_level}, nil, arg, &block)
+          else
+            if arg.nil?
+              add(#{log_level}, nil, context, &block)
+            elsif block
+              add(#{log_level}, nil, context) { "\#{arg}: \#{block.call}" }
+            else
+              add(#{log_level}, arg, context)
+            end
           end
         end
       EOS

spec/lib/contextual_logger_spec.rb

@@ -181,18 +181,35 @@ def expect_log_line_to_be_written(log_line)
   end
 
   context 'inline context' do
+    let(:message) { 'this is a test' }
     let(:expected_log_hash) do
       {
-        message: 'this is a test',
-        timestamp: Time.now
+        severity: 'INFO',
+        message: message,
+        timestamp: Time.now,
+        service: 'test_service'
       }
     end
 
-    it 'handles message block (inline context)' do
-      expect_log_line_to_be_written(expected_log_hash.merge(severity: 'INFO', service: 'test_service').to_json)
+    it 'handles message block (inline context) with nil progname' do
+      expect_log_line_to_be_written(expected_log_hash.to_json)
       expect(logger.info(nil, service: 'test_service') { 'this is a test' }).to eq(true)
     end
 
+    it 'handles message block (inline context) with no progname' do
+      expect_log_line_to_be_written(expected_log_hash.to_json)
+      expect(logger.info(service: 'test_service') { 'this is a test' }).to eq(true)
+    end
+
+    context 'with progname and message' do
+      let(:message) { 'request: this is a test' }
+
+      it 'handles message block (inline context) with progname' do
+        expect_log_line_to_be_written(expected_log_hash.to_json)
+        expect(logger.info('request', service: 'test_service') { 'this is a test' }).to eq(true)
+      end
+    end
+
     context "when log level isn't enabled" do
       before { logger.level = Logger::Severity::UNKNOWN }