diff --git a/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb b/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb
index b3a1c4734d3..3948c07c352 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb
@@ -61,6 +61,10 @@ module Gitlab
               data.length
             end
 
+            def append!(data)
+              raise NotImplementedError
+            end
+
             def truncate!(offset)
               raise NotImplementedError
             end
diff --git a/lib/gitlab/ci/trace/chunked_file/chunk_store/object_storage.rb b/lib/gitlab/ci/trace/chunked_file/chunk_store/object_storage.rb
index f144d670d03..95aaa9f9e2c 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunk_store/object_storage.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunk_store/object_storage.rb
@@ -65,6 +65,10 @@ module Gitlab
               raise NotImplementedError
             end
 
+            def append!(data)
+              raise NotImplementedError
+            end
+
             def truncate!(offset)
               raise NotImplementedError
             end
diff --git a/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb b/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb
index 6fa27b2c196..574657803dd 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb
@@ -74,6 +74,13 @@ module Gitlab
               end
             end
 
+            def append!(data)
+              Gitlab::Redis::Cache.with do |redis|
+                redis.append(buffer_key, data)
+                data.length
+              end
+            end
+
             def truncate!(offset)
               Gitlab::Redis::Cache.with do |redis|
                 return unless redis.exists(buffer_key)
diff --git a/lib/gitlab/ci/trace/chunked_file/chunked_io.rb b/lib/gitlab/ci/trace/chunked_file/chunked_io.rb
index 5c36158dbea..c3a84083eae 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunked_io.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunked_io.rb
@@ -1,12 +1,22 @@
 ##
-# This class is compatible with IO class (https://ruby-doc.org/core-2.3.1/IO.html)
-# source: https://gitlab.com/snippets/1685610
+# This class is designed as it's compatible with IO class (https://ruby-doc.org/core-2.3.1/IO.html)
 module Gitlab
   module Ci
     class Trace
       module ChunkedFile
         class ChunkedIO
+          class << self
+            def open(job_id, size, mode)
+              stream = self.new(job_id, size, mode)
+
+              yield stream
+            ensure
+              stream.close
+            end
+          end
+
           WriteError = Class.new(StandardError)
+          FailedToGetChunkError = Class.new(StandardError)
 
           attr_reader :size
           attr_reader :tell
@@ -23,7 +33,10 @@ module Gitlab
 
             if /(w|a)/ =~ mode
               @write_lock_uuid = Gitlab::ExclusiveLease.new(write_lock_key, timeout: 1.hour.to_i).try_obtain
+
               raise WriteError, 'Already opened by another process' unless write_lock_uuid
+
+              seek(0, IO::SEEK_END) if /a/ =~ mode
             end
           end
 
@@ -39,10 +52,6 @@ module Gitlab
             true
           end
 
-          def path
-            nil
-          end
-
           def seek(pos, where = IO::SEEK_SET)
             new_pos =
               case where
@@ -111,46 +120,56 @@ module Gitlab
           end
 
           def write(data, &block)
-            raise WriteError, 'Already opened by another process' unless write_lock_uuid
+            raise WriteError, 'Could not write without lock' unless write_lock_uuid
+            raise WriteError, 'Could not write empty data' unless data.present?
 
-            while data.present?
-              empty_space = BUFFER_SIZE - chunk_offset
+            data = data.dup
 
-              chunk_store.open(job_id, chunk_index, params_for_store) do |store|
-                data_to_write = ''
-                data_to_write += store.get if store.size > 0
-                data_to_write += data.slice!(0..empty_space)
+            chunk_index_start = chunk_index
+            chunk_index_end = (tell + data.length) / BUFFER_SIZE
+            prev_tell = tell
 
-                written_size = store.write!(data_to_write)
+            (chunk_index_start..chunk_index_end).each do |c_index|
+              chunk_store.open(job_id, c_index, params_for_store) do |store|
+                writable_space = BUFFER_SIZE - chunk_offset
+                writing_size = [writable_space, data.length].min
 
-                raise WriteError, 'Written size mismatch' unless data_to_write.length == written_size
+                if store.size > 0
+                  written_size = store.append!(data.slice!(0...writing_size))
+                else
+                  written_size = store.write!(data.slice!(0...writing_size))
+                end
 
-                block.call(store, chunk_index) if block_given?
+                raise WriteError, 'Written size mismatch' unless writing_size == written_size
 
                 @tell += written_size
-                @size += written_size
+                @size = [tell, size].max
+
+                block.call(store, c_index) if block_given?
               end
             end
+
+            tell - prev_tell
           end
 
-          def truncate(offset)
-            raise WriteError, 'Already opened by another process' unless write_lock_uuid
+          def truncate(offset, &block)
+            raise WriteError, 'Could not write without lock' unless write_lock_uuid
+            raise WriteError, 'Offset is out of bound' if offset > size || offset < 0
 
-            removal_chunk_index_start = (offset / BUFFER_SIZE)
-            removal_chunk_index_end = chunks_count - 1
-            removal_chunk_offset = offset % BUFFER_SIZE
+            chunk_index_start = (offset / BUFFER_SIZE)
+            chunk_index_end = chunks_count - 1
 
-            if removal_chunk_offset > 0
-              chunk_store.open(job_id, removal_chunk_index_start, params_for_store) do |store|
-                store.truncate!(removal_chunk_offset)
-              end
+            (chunk_index_start..chunk_index_end).reverse_each do |c_index|
+              chunk_store.open(job_id, c_index, params_for_store) do |store|
+                c_index_start = c_index * BUFFER_SIZE
 
-              removal_chunk_index_start += 1
-            end
+                if offset <= c_index_start
+                  store.delete!
+                else
+                  store.truncate!(offset - c_index_start) if store.size > 0
+                end
 
-            (removal_chunk_index_start..removal_chunk_index_end).each do |removal_chunk_index|
-              chunk_store.open(job_id, removal_chunk_index, params_for_store) do |store|
-                store.delete!
+                block.call(store, c_index) if block_given?
               end
             end
 
@@ -165,15 +184,8 @@ module Gitlab
             true
           end
 
-          def delete_chunks!
-            truncate(0)
-          end
-
           private
 
-          ##
-          # The below methods are not implemented in IO class
-          #
           def in_range?
             @chunk_range&.include?(tell)
           end
@@ -182,7 +194,10 @@ module Gitlab
             unless in_range?
               chunk_store.open(job_id, chunk_index, params_for_store) do |store|
                 @chunk = store.get
-                @chunk_range = (chunk_start...(chunk_start + @chunk.length))
+
+                raise FailedToGetChunkError unless chunk
+
+                @chunk_range = (chunk_start...(chunk_start + chunk.length))
               end
             end
 
@@ -223,6 +238,10 @@ module Gitlab
           def write_lock_key
             "live_trace:operation:write:#{job_id}"
           end
+
+          def chunk_store
+            raise NotImplementedError
+          end
         end
       end
     end
diff --git a/lib/gitlab/ci/trace/chunked_file/live_trace.rb b/lib/gitlab/ci/trace/chunked_file/live_trace.rb
index 7c39561bec7..081ae6e8d51 100644
--- a/lib/gitlab/ci/trace/chunked_file/live_trace.rb
+++ b/lib/gitlab/ci/trace/chunked_file/live_trace.rb
@@ -7,7 +7,7 @@ module Gitlab
 
           class << self
             def open(job_id, mode)
-              stream = self.class.new(job_id, mode)
+              stream = self.new(job_id, mode)
 
               yield stream
             ensure
diff --git a/lib/gitlab/ci/trace/chunked_file/remote.rb b/lib/gitlab/ci/trace/chunked_file/remote.rb
index 56ff05c7494..caa2235bdbd 100644
--- a/lib/gitlab/ci/trace/chunked_file/remote.rb
+++ b/lib/gitlab/ci/trace/chunked_file/remote.rb
@@ -6,11 +6,11 @@ module Gitlab
           BUFFER_SIZE = 128.kilobytes
 
           class << self
-            def open(job_id, url, size, mode)
-              stream = self.class.new(job_id, mode)
+            def open(job_id, mode)
+              stream = self.new(job_id, mode)
 
               yield stream
-
+            ensure
               stream.close
             end
           end
diff --git a/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb b/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb
new file mode 100644
index 00000000000..506ce71099a
--- /dev/null
+++ b/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb
@@ -0,0 +1,481 @@
+require 'spec_helper'
+
+describe Gitlab::Ci::Trace::ChunkedFile::ChunkedIO, :clean_gitlab_redis_cache do
+  include ChunkedIOHelpers
+
+  let(:chunked_io) { described_class.new(job_id, size, mode) }
+  let(:job_id) { 1 }
+  let(:size) { sample_trace_size }
+  let(:mode) { 'rb' }
+  let(:buffer_size) { 128.kilobytes }
+  let(:chunk_store) { Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis }
+
+  before do
+    allow_any_instance_of(described_class).to receive(:chunk_store).and_return(chunk_store)
+    stub_const("Gitlab::Ci::Trace::ChunkedFile::ChunkedIO::BUFFER_SIZE", buffer_size)
+  end
+
+  describe '#new' do
+    context 'when mode is read' do
+      let(:mode) { 'rb' }
+
+      it 'raises no exception' do
+        described_class.new(job_id, size, mode)
+
+        expect { described_class.new(job_id, size, mode) }.not_to raise_error
+      end
+    end
+
+    context 'when mode is write' do
+      let(:mode) { 'a+b' }
+
+      it 'raises an exception' do
+        described_class.new(job_id, size, mode)
+
+        expect { described_class.new(job_id, size, mode) }.to raise_error('Already opened by another process')
+      end
+
+      context 'when closed after open' do
+        it 'does not raise an exception' do
+          described_class.new(job_id, size, mode).close
+
+          expect { described_class.new(job_id, size, mode) }.not_to raise_error
+        end
+      end
+    end
+  end
+
+  describe '#seek' do
+    subject { chunked_io.seek(pos, where) }
+
+    context 'when moves pos to end of the file' do
+      let(:pos) { 0 }
+      let(:where) { IO::SEEK_END }
+
+      it { is_expected.to eq(size) }
+    end
+
+    context 'when moves pos to middle of the file' do
+      let(:pos) { size / 2 }
+      let(:where) { IO::SEEK_SET }
+
+      it { is_expected.to eq(size / 2) }
+    end
+
+    context 'when moves pos around' do
+      it 'matches the result' do
+        expect(chunked_io.seek(0)).to eq(0)
+        expect(chunked_io.seek(100, IO::SEEK_CUR)).to eq(100)
+        expect { chunked_io.seek(size + 1, IO::SEEK_CUR) }.to raise_error('new position is outside of file')
+      end
+    end
+  end
+
+  describe '#eof?' do
+    subject { chunked_io.eof? }
+
+    context 'when current pos is at end of the file' do
+      before do
+        chunked_io.seek(size, IO::SEEK_SET)
+      end
+
+      it { is_expected.to be_truthy }
+    end
+
+    context 'when current pos is not at end of the file' do
+      before do
+        chunked_io.seek(0, IO::SEEK_SET)
+      end
+
+      it { is_expected.to be_falsey }
+    end
+  end
+
+  describe '#each_line' do
+    let(:buffer_size) { 128.kilobytes }
+    let(:string_io) { StringIO.new(sample_trace_raw) }
+
+    context 'when BUFFER_SIZE is smaller than file size' do
+      before do
+        set_smaller_buffer_size_than(size)
+        fill_trace_to_chunks(sample_trace_raw)
+      end
+
+      it 'yields lines' do
+        expect { |b| described_class.new(job_id, size, 'rb').each_line(&b) }
+          .to yield_successive_args(*string_io.each_line.to_a)
+      end
+    end
+
+    context 'when BUFFER_SIZE is larger than file size' do
+      let(:buffer_size) { size + 1000 }
+
+      before do
+        set_larger_buffer_size_than(size)
+        fill_trace_to_chunks(sample_trace_raw)
+      end
+
+      it 'calls get_chunk only once' do
+        expect(chunk_store).to receive(:open).once.and_call_original
+
+        described_class.new(job_id, size, 'rb').each_line { |line| }
+      end
+    end
+  end
+
+  describe '#read' do
+    subject { described_class.new(job_id, size, 'rb').read(length) }
+
+    context 'when read whole size' do
+      let(:length) { nil }
+
+      context 'when BUFFER_SIZE is smaller than file size', :clean_gitlab_redis_cache do
+        before do
+          set_smaller_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to eq(sample_trace_raw)
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size', :clean_gitlab_redis_cache do
+        before do
+          set_larger_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to eq(sample_trace_raw)
+        end
+      end
+    end
+
+    context 'when read only first 100 bytes' do
+      let(:length) { 100 }
+
+      context 'when BUFFER_SIZE is smaller than file size', :clean_gitlab_redis_cache do
+        before do
+          set_smaller_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to eq(sample_trace_raw[0, length])
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size', :clean_gitlab_redis_cache do
+        before do
+          set_larger_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to eq(sample_trace_raw[0, length])
+        end
+      end
+    end
+
+    context 'when tries to read oversize' do
+      let(:length) { size + 1000 }
+
+      context 'when BUFFER_SIZE is smaller than file size' do
+        before do
+          set_smaller_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to eq(sample_trace_raw)
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size' do
+        before do
+          set_larger_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to eq(sample_trace_raw)
+        end
+      end
+    end
+
+    context 'when tries to read 0 bytes' do
+      let(:length) { 0 }
+
+      context 'when BUFFER_SIZE is smaller than file size' do
+        before do
+          set_smaller_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to be_empty
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size' do
+        before do
+          set_larger_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'reads a trace' do
+          is_expected.to be_empty
+        end
+      end
+    end
+
+    context 'when chunk store failed to get chunk' do
+      let(:length) { nil }
+
+      before do
+        fill_trace_to_chunks(sample_trace_raw)
+
+        stub_chunk_store_redis_get_failed
+      end
+
+      it 'reads a trace' do
+        expect { subject }.to raise_error(Gitlab::Ci::Trace::ChunkedFile::ChunkedIO::FailedToGetChunkError)
+      end
+    end
+  end
+
+  describe '#readline' do
+    subject { chunked_io.readline }
+
+    let(:string_io) { StringIO.new(sample_trace_raw) }
+
+    shared_examples 'all line matching' do
+      it 'reads a line' do
+        (0...sample_trace_raw.lines.count).each do
+          expect(chunked_io.readline).to eq(string_io.readline)
+        end
+      end
+    end
+
+    context 'when chunk store failed to get chunk' do
+      let(:length) { nil }
+
+      before do
+        fill_trace_to_chunks(sample_trace_raw)
+        stub_chunk_store_redis_get_failed
+      end
+
+      it 'reads a trace' do
+        expect { subject }.to raise_error(Gitlab::Ci::Trace::ChunkedFile::ChunkedIO::FailedToGetChunkError)
+      end
+    end
+
+    context 'when BUFFER_SIZE is smaller than file size' do
+      before do
+        set_smaller_buffer_size_than(size)
+        fill_trace_to_chunks(sample_trace_raw)
+      end
+
+      it_behaves_like 'all line matching'
+    end
+
+    context 'when BUFFER_SIZE is larger than file size' do
+      before do
+        set_larger_buffer_size_than(size)
+        fill_trace_to_chunks(sample_trace_raw)
+      end
+
+      it_behaves_like 'all line matching'
+    end
+
+    context 'when pos is at middle of the file' do
+      before do
+        set_smaller_buffer_size_than(size)
+        fill_trace_to_chunks(sample_trace_raw)
+
+        chunked_io.seek(size / 2)
+        string_io.seek(size / 2)
+      end
+
+      it 'reads from pos' do
+        expect(chunked_io.readline).to eq(string_io.readline)
+      end
+    end
+  end
+
+  describe '#write' do
+    subject { chunked_io.write(data) }
+
+    let(:data) { sample_trace_raw }
+
+    context 'when write mdoe' do
+      let(:mode) { 'wb' }
+
+      context 'when BUFFER_SIZE is smaller than file size', :clean_gitlab_redis_cache do
+        before do
+          set_smaller_buffer_size_than(size)
+        end
+
+        it 'writes a trace' do
+          is_expected.to eq(data.length)
+
+          Gitlab::Ci::Trace::ChunkedFile::ChunkedIO.open(job_id, size, 'rb') do |stream|
+            expect(stream.read).to eq(data)
+            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+            expect(chunk_store.chunks_size(job_id)).to eq(data.length)
+          end
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size', :clean_gitlab_redis_cache do
+        before do
+          set_larger_buffer_size_than(size)
+        end
+
+        it 'writes a trace' do
+          is_expected.to eq(data.length)
+
+          Gitlab::Ci::Trace::ChunkedFile::ChunkedIO.open(job_id, size, 'rb') do |stream|
+            expect(stream.read).to eq(data)
+            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+            expect(chunk_store.chunks_size(job_id)).to eq(data.length)
+          end
+        end
+      end
+
+      context 'when data is nil' do
+        let(:data) { nil }
+
+        it 'writes a trace' do
+          expect { subject } .to raise_error('Could not write empty data')
+        end
+      end
+    end
+
+    context 'when append mdoe' do
+      let(:original_data) { 'original data' }
+      let(:total_size) { original_data.length + data.length }
+
+      context 'when BUFFER_SIZE is smaller than file size', :clean_gitlab_redis_cache do
+        before do
+          set_smaller_buffer_size_than(size)
+          fill_trace_to_chunks(original_data)
+        end
+
+        it 'appends a trace' do
+          described_class.open(job_id, original_data.length, 'a+b') do |stream|
+            expect(stream.write(data)).to eq(data.length)
+          end
+
+          described_class.open(job_id, total_size, 'rb') do |stream|
+            expect(stream.read).to eq(original_data + data)
+            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+            expect(chunk_store.chunks_size(job_id)).to eq(total_size)
+          end
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size', :clean_gitlab_redis_cache do
+        before do
+          set_larger_buffer_size_than(size)
+          fill_trace_to_chunks(original_data)
+        end
+
+        it 'appends a trace' do
+          described_class.open(job_id, original_data.length, 'a+b') do |stream|
+            expect(stream.write(data)).to eq(data.length)
+          end
+
+          described_class.open(job_id, total_size, 'rb') do |stream|
+            expect(stream.read).to eq(original_data + data)
+            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+            expect(chunk_store.chunks_size(job_id)).to eq(total_size)
+          end
+        end
+      end
+    end
+  end
+
+  describe '#truncate' do
+    context 'when data exists' do
+      context 'when BUFFER_SIZE is smaller than file size', :clean_gitlab_redis_cache do
+        before do
+          set_smaller_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'truncates a trace' do
+          described_class.open(job_id, size, 'rb') do |stream|
+            expect(stream.read).to eq(sample_trace_raw)
+          end
+
+          described_class.open(job_id, size, 'wb') do |stream|
+            stream.truncate(0)
+          end
+
+          described_class.open(job_id, 0, 'rb') do |stream|
+            expect(stream.read).to be_empty
+          end
+
+          expect(chunk_store.chunks_count(job_id)).to eq(0)
+          expect(chunk_store.chunks_size(job_id)).to eq(0)
+        end
+
+        context 'when offset is negative', :clean_gitlab_redis_cache do
+          it 'raises an error' do
+            described_class.open(job_id, size, 'wb') do |stream|
+              expect { stream.truncate(-1) }.to raise_error('Offset is out of bound')
+            end
+          end
+        end
+
+        context 'when offset is larger than file size', :clean_gitlab_redis_cache do
+          it 'raises an error' do
+            described_class.open(job_id, size, 'wb') do |stream|
+              expect { stream.truncate(size + 1) }.to raise_error('Offset is out of bound')
+            end
+          end
+        end
+      end
+
+      context 'when BUFFER_SIZE is larger than file size', :clean_gitlab_redis_cache do
+        before do
+          set_larger_buffer_size_than(size)
+          fill_trace_to_chunks(sample_trace_raw)
+        end
+
+        it 'truncates a trace' do
+          described_class.open(job_id, size, 'rb') do |stream|
+            expect(stream.read).to eq(sample_trace_raw)
+          end
+
+          described_class.open(job_id, size, 'wb') do |stream|
+            stream.truncate(0)
+          end
+
+          described_class.open(job_id, 0, 'rb') do |stream|
+            expect(stream.read).to be_empty
+          end
+
+          expect(chunk_store.chunks_count(job_id)).to eq(0)
+          expect(chunk_store.chunks_size(job_id)).to eq(0)
+        end
+      end
+    end
+
+    context 'when data does not exist' do
+      before do
+        set_smaller_buffer_size_than(size)
+      end
+
+      it 'truncates a trace' do
+        described_class.open(job_id, size, 'wb') do |stream|
+          stream.truncate(0)
+          expect(stream.send(:tell)).to eq(0)
+          expect(stream.send(:size)).to eq(0)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/support/chunked_io/chunked_io_helpers.rb b/spec/support/chunked_io/chunked_io_helpers.rb
new file mode 100644
index 00000000000..d87483620e5
--- /dev/null
+++ b/spec/support/chunked_io/chunked_io_helpers.rb
@@ -0,0 +1,32 @@
+module ChunkedIOHelpers
+  def fill_trace_to_chunks(data)
+    stream = Gitlab::Ci::Trace::ChunkedFile::ChunkedIO.new(job_id, data.length, 'wb')
+    stream.write(data)
+    stream.close
+  end
+
+  def sample_trace_raw
+    @sample_trace_raw ||= File.read(expand_fixture_path('trace/sample_trace'))
+  end
+
+  def sample_trace_size
+    sample_trace_raw.length
+  end
+
+  def stub_chunk_store_redis_get_failed
+    allow_any_instance_of(Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis)
+      .to receive(:get).and_return(nil)
+  end
+
+  def set_smaller_buffer_size_than(file_size)
+    blocks = (file_size / 128)
+    new_size = (blocks / 2) * 128
+    stub_const("Gitlab::Ci::Trace::ChunkedFile::ChunkedIO::BUFFER_SIZE", new_size)
+  end
+
+  def set_larger_buffer_size_than(file_size)
+    blocks = (file_size / 128)
+    new_size = (blocks * 2) * 128
+    stub_const("Gitlab::Ci::Trace::ChunkedFile::ChunkedIO::BUFFER_SIZE", new_size)
+  end
+end