Added spec for build trace chunk

app/models/ci/build_trace_chunk.rb

@@ -8,8 +8,6 @@ module Ci
 
     default_value_for :data_store, :redis
 
-    WriteError = Class.new(StandardError)
-
     CHUNK_SIZE = 128.kilobytes
     WRITE_LOCK_RETRY = 10
     WRITE_LOCK_SLEEP = 0.01.seconds
@@ -65,6 +63,7 @@ module Ci
     end
 
     def truncate(offset = 0)
+      raise ArgumentError, 'Fog store does not support truncating' if fog? # If data is null, get_data returns Excon::Error::NotFound
       raise ArgumentError, 'Offset is out of range' if offset > size || offset < 0
       return if offset == size # Skip the following process as it doesn't affect anything
 
@@ -72,6 +71,8 @@ module Ci
     end
 
     def append(new_data, offset)
+      raise ArgumentError, 'Fog store does not support appending' if fog? # If data is null, get_data returns Excon::Error::NotFound
+      raise ArgumentError, 'New data is nil' unless new_data
       raise ArgumentError, 'Offset is out of range' if offset > size || offset < 0
       raise ArgumentError, 'Chunk size overflow' if CHUNK_SIZE < (offset + new_data.bytesize)
 
@@ -98,21 +99,17 @@ module Ci
       (start_offset...end_offset)
     end
 
-    def data_persisted?
-      !redis?
-    end
-
     def persist_data!
       in_lock(*lock_params) do # Write opetation is atomic
-        unsafe_migrate_to!(self.class.persist_store)
+        unsafe_persist_to!(self.class.persist_store)
       end
     end
 
     private
 
-    def unsafe_migrate_to!(new_store)
+    def unsafe_persist_to!(new_store)
       return if data_store == new_store.to_s
-      return unless size > 0
+      raise ArgumentError, 'Can not persist empty data' unless size > 0
 
       old_store_class = self.class.get_store_class(data_store)
 
@@ -130,7 +127,7 @@ module Ci
     end
 
     def unsafe_set_data!(value)
-      raise ArgumentError, 'too much data' if value.bytesize > CHUNK_SIZE
+      raise ArgumentError, 'New data size exceeds chunk size' if value.bytesize > CHUNK_SIZE
 
       self.class.get_store_class(data_store).set_data(self, value)
       @data = value
@@ -144,6 +141,10 @@ module Ci
       Ci::BuildTraceChunkFlushWorker.perform_async(id)
     end
 
+    def data_persisted?
+      !redis?
+    end
+
     def full?
       size == CHUNK_SIZE
     end

app/services/concerns/exclusive_lease_lock.rb

 module ExclusiveLeaseLock
   extend ActiveSupport::Concern
 
+  FailedToObtainLockError = Class.new(StandardError)
+
   def in_lock(key, ttl: 1.minute, retry_max: 10, sleep_sec: 0.01.seconds)
     lease = Gitlab::ExclusiveLease.new(key, timeout: ttl)
     retry_count = 0
@@ -12,7 +14,7 @@ module ExclusiveLeaseLock
       break if retry_max < (retry_count += 1)
     end
 
-    raise WriteError, 'Failed to obtain write lock' unless uuid
+    raise FailedToObtainLockError, 'Failed to obtain a lock' unless uuid
 
     return yield
   ensure

spec/support/helpers/stub_object_storage.rb

@@ -20,6 +20,11 @@ module StubObjectStorage
     ::Fog::Storage.new(uploader.object_store_credentials).tap do |connection|
       begin
         connection.directories.create(key: remote_directory)
+
+        # Cleanup remaining files
+        connection.directories.each do |directory|
+          directory.files.map(&:destroy)
+        end
       rescue Excon::Error::Conflict
       end
     end