Use the configuration context even if it's 'nil'

This allows users to opt out of automatic context setting without
having to set their own context for all events

lib/bugsnag/configuration.rb

@@ -553,6 +553,18 @@ def remove_on_breadcrumb(callback)
       @on_breadcrumb_callbacks.remove(callback)
     end
 
+    ##
+    # Has the context been explicitly set?
+    #
+    # This is necessary to differentiate between the context not being set and
+    # the context being set to 'nil' explicitly
+    #
+    # @api private
+    # @return [Boolean]
+    def context_set?
+      defined?(@context) != nil
+    end
+
     # TODO: These methods can be a simple attr_accessor when they replace the
     #       methods they are aliasing
     # NOTE: they are not aliases as YARD doesn't allow documenting the non-alias

lib/bugsnag/report.rb

@@ -114,7 +114,7 @@ def initialize(exception, passed_configuration, auto_notify=false)
       self.app_type = configuration.app_type
       self.app_version = configuration.app_version
       self.breadcrumbs = []
-      self.context = configuration.context
+      self.context = configuration.context if configuration.context_set?
       self.delivery_method = configuration.delivery_method
       self.hostname = configuration.hostname
       self.runtime_versions = configuration.runtime_versions.dup
@@ -130,7 +130,9 @@ def initialize(exception, passed_configuration, auto_notify=false)
     # @!attribute context
     # @return [String, nil]
     def context
-      @context || @automatic_context
+      return @context if defined?(@context)
+
+      @automatic_context
     end
 
     attr_writer :context

spec/report_spec.rb

@@ -610,6 +610,21 @@ def gloops
     })
   end
 
+  it "uses overridden context even it is set to 'nil'" do
+    Bugsnag.configure do |config|
+      config.context = nil
+    end
+
+    Bugsnag.notify(BugsnagTestException.new("It crashed")) do |report|
+      report.automatic_context = "automatic context"
+    end
+
+    expect(Bugsnag).to(have_sent_notification { |payload, _headers|
+      event = get_event_from_payload(payload)
+      expect(event["context"]).to be_nil
+    })
+  end
+
   it "uses the context from Configuration, if set" do
     Bugsnag.configure do |config|
       config.context = "example context"