Merge branch 'feature/reduce-test-flakiness'

lib/retry_on_error.rb

@@ -1,11 +1,12 @@
 module RetryOnError
-  def retry_on_error(errors:, limit: 10)
+  def retry_on_error(errors:, limit: 10, on_error: nil)
     tries ||= 1
     yield
   rescue *errors => e
     if tries < limit
       message = "#{e}, attempt #{tries} of #{limit}"
       Imap::Backup::Logger.logger.debug message
+      on_error&.call
       tries += 1
       retry
     end

spec/features/support/20_test_email_server.rb

@@ -1,7 +1,9 @@
+require "retry_on_error"
 require_relative "10_server_message_helpers"
 
 class TestEmailServer
   include ServerMessageHelpers
+  include RetryOnError
 
   REQUESTED_ATTRIBUTES = [BODY_ATTRIBUTE, "FLAGS"].freeze
 
@@ -49,24 +51,18 @@ def root_folder
   end
 
   def folders
-    # Reconnect if necessary to avoid '#<IOError: closed stream>'
-    reconnect
-    imap.list(root_folder, "*")
+    retry_on_error(errors: [::IOError], limit: 2, on_error: -> { reconnect }) do
+      imap.list(root_folder, "*")
+    end
   end
 
   def create_folder(folder)
-    # Reconnect if necessary to avoid '#<IOError: closed stream>'
-    reconnect
-
     return if folder_exists?(folder)
 
     imap.create(folder)
   end
 
   def delete_folder(folder)
-    # Reconnect if necessary to avoid '#<IOError: closed stream>'
-    reconnect
-
     return if !folder_exists?(folder)
 
     # N.B. If we are deleting the currently selected folder
@@ -129,7 +125,9 @@ def fetch_email(folder, uid)
   end
 
   def examine(folder)
-    imap.examine(folder)
+    retry_on_error(errors: [::IOError], limit: 2, on_error: -> { reconnect }) do
+      imap.examine(folder)
+    end
   end
 
   def folder_uid_validity(folder)

spec/unit/retry_on_error_spec.rb

@@ -3,12 +3,12 @@ class FooError < StandardError; end
 
   include RetryOnError
 
-  def do_stuff(errors:, limit:)
+  def do_stuff(errors:, limit: 10, on_error: nil)
     calls = 0
 
-    retry_on_error(errors: errors, limit: limit) do
+    retry_on_error(errors: errors, limit: limit, on_error: on_error) do
       calls += 1
-      raise FooError if calls < 3
+      raise FooError, "Failed!" if calls < 3
 
       42
     end
@@ -27,7 +27,25 @@ def do_stuff(errors:, limit:)
       it "fails" do
         expect do
           subject.do_stuff(errors: [Retrier::FooError], limit: 1)
-        end.to raise_error(Retrier::FooError)
+        end.to raise_error(Retrier::FooError, /Failed/)
+      end
+    end
+
+    context "when unexpected errors are raised" do
+      it "fails" do
+        expect do
+          subject.do_stuff(errors: [RuntimeError])
+        end.to raise_error(Retrier::FooError, /Failed/)
+      end
+    end
+
+    context "when an :on_error block is passed" do
+      it "calls the block before retrying" do
+        on_error_calls = 0
+        error_proc = -> { on_error_calls += 1 }
+        subject.do_stuff(errors: [Retrier::FooError], on_error: error_proc)
+
+        expect(on_error_calls).to eq(2)
       end
     end
   end