Add SignalException to default ignore_classes

With #397 we receive SignalException error reports when puma shuts down,
which aren't really errors.

lib/bugsnag/configuration.rb

@@ -69,9 +69,9 @@ def initialize
       self.auto_capture_sessions = false
       self.session_endpoint = DEFAULT_SESSION_ENDPOINT
 
-      # SystemExit and Interrupt are common Exception types seen with successful
-      # exits and are not automatically reported to Bugsnag
-      self.ignore_classes = Set.new([SystemExit, Interrupt])
+      # SystemExit and SignalException are common Exception types seen with
+      # successful exits and are not automatically reported to Bugsnag
+      self.ignore_classes = Set.new([SystemExit, SignalException])
 
       # Read the API key from the environment
       self.api_key = ENV["BUGSNAG_API_KEY"]

spec/configuration_spec.rb

@@ -219,7 +219,7 @@ def debug(name, &block)
   end
 
   it "should have exit exception classes ignored by default" do
-    expect(subject.ignore_classes).to eq(Set.new([SystemExit, Interrupt]))
+    expect(subject.ignore_classes).to eq(Set.new([SystemExit, SignalException]))
   end
 
 end

spec/report_spec.rb

@@ -146,18 +146,27 @@ def gloops
   end
 
   it "sets correct severity and reason for specific error classes" do
-    Bugsnag.notify(SignalException.new("TERM"))
-    expect(Bugsnag).to have_sent_notification{ |payload, headers|
-      event = get_event_from_payload(payload)
-      expect(event["unhandled"]).to be false
-      expect(event["severity"]).to eq("info")
-      expect(event["severityReason"]).to eq({
-        "type" => "errorClass",
-        "attributes" => {
-          "errorClass" => "SignalException"
-        }
-      })
-    }
+    original_ignore_classes = Bugsnag.configuration.ignore_classes
+
+    begin
+      # The default ignore_classes includes SignalException, so we need to
+      # temporarily set it to something else.
+      Bugsnag.configuration.ignore_classes = Set[SystemExit]
+      Bugsnag.notify(SignalException.new("TERM"))
+      expect(Bugsnag).to have_sent_notification{ |payload, headers|
+        event = get_event_from_payload(payload)
+        expect(event["unhandled"]).to be false
+        expect(event["severity"]).to eq("info")
+        expect(event["severityReason"]).to eq({
+          "type" => "errorClass",
+          "attributes" => {
+            "errorClass" => "SignalException"
+          }
+        })
+      }
+    ensure
+      Bugsnag.configuration.ignore_classes = original_ignore_classes
+    end
   end
 
   # TODO: nested context
@@ -1052,10 +1061,10 @@ def gloops
       expect(exception["message"]).to eq("'nil' was notified as an exception")
 
       stacktrace = exception["stacktrace"][0]
-      expect(stacktrace["lineNumber"]).to eq(1047)
+      expect(stacktrace["lineNumber"]).to eq(1056)
       expect(stacktrace["file"]).to end_with("spec/report_spec.rb")
-      expect(stacktrace["code"]["1046"]).to eq("  it 'uses an appropriate message if nil is notified' do")
-      expect(stacktrace["code"]["1047"]).to eq("    Bugsnag.notify(nil)")
+      expect(stacktrace["code"]["1055"]).to eq("  it 'uses an appropriate message if nil is notified' do")
+      expect(stacktrace["code"]["1056"]).to eq("    Bugsnag.notify(nil)")
     }
   end