Merge branch 'make-relative-positioning-module-reusable' into 'master'

Make RelativePositioning reusable

See merge request gitlab-org/gitlab-ce!30993

1 files changed, 253 insertions, 0 deletions

diff --git a/spec/support/shared_examples/relative_positioning_shared_examples.rb b/spec/support/shared_examples/relative_positioning_shared_examples.rb
new file mode 100644
index 00000000000..5ee62644c54
--- /dev/null
+++ b/spec/support/shared_examples/relative_positioning_shared_examples.rb
@@ -0,0 +1,253 @@
+# frozen_string_literal: true
+
+RSpec.shared_examples "a class that supports relative positioning" do
+  let(:item1) { create(factory, default_params) }
+  let(:item2) { create(factory, default_params) }
+  let(:new_item) { create(factory, default_params) }
+
+  def create_item(params)
+    create(factory, params.merge(default_params))
+  end
+
+  describe '.move_to_end' do
+    it 'moves the object to the end' do
+      item1.update(relative_position: 5)
+      item2.update(relative_position: 15)
+
+      described_class.move_to_end([item1, item2])
+
+      expect(item2.prev_relative_position).to eq item1.relative_position
+      expect(item1.prev_relative_position).to eq nil
+      expect(item2.next_relative_position).to eq nil
+    end
+
+    it 'does not perform any moves if all items have their relative_position set' do
+      item1.update!(relative_position: 1)
+
+      expect(item1).not_to receive(:save)
+
+      described_class.move_to_end([item1])
+    end
+  end
+
+  describe '#max_relative_position' do
+    it 'returns maximum position' do
+      expect(item1.max_relative_position).to eq item2.relative_position
+    end
+  end
+
+  describe '#prev_relative_position' do
+    it 'returns previous position if there is an item above' do
+      item1.update(relative_position: 5)
+      item2.update(relative_position: 15)
+
+      expect(item2.prev_relative_position).to eq item1.relative_position
+    end
+
+    it 'returns nil if there is no item above' do
+      expect(item1.prev_relative_position).to eq nil
+    end
+  end
+
+  describe '#next_relative_position' do
+    it 'returns next position if there is an item below' do
+      item1.update(relative_position: 5)
+      item2.update(relative_position: 15)
+
+      expect(item1.next_relative_position).to eq item2.relative_position
+    end
+
+    it 'returns nil if there is no item below' do
+      expect(item2.next_relative_position).to eq nil
+    end
+  end
+
+  describe '#move_before' do
+    it 'moves item before' do
+      [item2, item1].each(&:move_to_end)
+
+      item1.move_before(item2)
+
+      expect(item1.relative_position).to be < item2.relative_position
+    end
+  end
+
+  describe '#move_after' do
+    it 'moves item after' do
+      [item1, item2].each(&:move_to_end)
+
+      item1.move_after(item2)
+
+      expect(item1.relative_position).to be > item2.relative_position
+    end
+  end
+
+  describe '#move_to_end' do
+    before do
+      [item1, item2].each do |item1|
+        item1.move_to_end && item1.save
+      end
+    end
+
+    it 'moves item to the end' do
+      new_item.move_to_end
+
+      expect(new_item.relative_position).to be > item2.relative_position
+    end
+  end
+
+  describe '#shift_after?' do
+    before do
+      [item1, item2].each do |item1|
+        item1.move_to_end && item1.save
+      end
+    end
+
+    it 'returns true' do
+      item1.update(relative_position: item2.relative_position - 1)
+
+      expect(item1.shift_after?).to be_truthy
+    end
+
+    it 'returns false' do
+      item1.update(relative_position: item2.relative_position - 2)
+
+      expect(item1.shift_after?).to be_falsey
+    end
+  end
+
+  describe '#shift_before?' do
+    before do
+      [item1, item2].each do |item1|
+        item1.move_to_end && item1.save
+      end
+    end
+
+    it 'returns true' do
+      item1.update(relative_position: item2.relative_position + 1)
+
+      expect(item1.shift_before?).to be_truthy
+    end
+
+    it 'returns false' do
+      item1.update(relative_position: item2.relative_position + 2)
+
+      expect(item1.shift_before?).to be_falsey
+    end
+  end
+
+  describe '#move_between' do
+    before do
+      [item1, item2].each do |item1|
+        item1.move_to_end && item1.save
+      end
+    end
+
+    it 'positions item between two other' do
+      new_item.move_between(item1, item2)
+
+      expect(new_item.relative_position).to be > item1.relative_position
+      expect(new_item.relative_position).to be < item2.relative_position
+    end
+
+    it 'positions item between on top' do
+      new_item.move_between(nil, item1)
+
+      expect(new_item.relative_position).to be < item1.relative_position
+    end
+
+    it 'positions item between to end' do
+      new_item.move_between(item2, nil)
+
+      expect(new_item.relative_position).to be > item2.relative_position
+    end
+
+    it 'positions items even when after and before positions are the same' do
+      item2.update relative_position: item1.relative_position
+
+      new_item.move_between(item1, item2)
+
+      expect(new_item.relative_position).to be > item1.relative_position
+      expect(item1.relative_position).to be < item2.relative_position
+    end
+
+    it 'positions items between other two if distance is 1' do
+      item2.update relative_position: item1.relative_position + 1
+
+      new_item.move_between(item1, item2)
+
+      expect(new_item.relative_position).to be > item1.relative_position
+      expect(item1.relative_position).to be < item2.relative_position
+    end
+
+    it 'positions item in the middle of other two if distance is big enough' do
+      item1.update relative_position: 6000
+      item2.update relative_position: 10000
+
+      new_item.move_between(item1, item2)
+
+      expect(new_item.relative_position).to eq(8000)
+    end
+
+    it 'positions item closer to the middle if we are at the very top' do
+      item2.update relative_position: 6000
+
+      new_item.move_between(nil, item2)
+
+      expect(new_item.relative_position).to eq(6000 - RelativePositioning::IDEAL_DISTANCE)
+    end
+
+    it 'positions item closer to the middle if we are at the very bottom' do
+      new_item.update relative_position: 1
+      item1.update relative_position: 6000
+      item2.destroy
+
+      new_item.move_between(item1, nil)
+
+      expect(new_item.relative_position).to eq(6000 + RelativePositioning::IDEAL_DISTANCE)
+    end
+
+    it 'positions item in the middle of other two if distance is not big enough' do
+      item1.update relative_position: 100
+      item2.update relative_position: 400
+
+      new_item.move_between(item1, item2)
+
+      expect(new_item.relative_position).to eq(250)
+    end
+
+    it 'positions item in the middle of other two is there is no place' do
+      item1.update relative_position: 100
+      item2.update relative_position: 101
+
+      new_item.move_between(item1, item2)
+
+      expect(new_item.relative_position).to be_between(item1.relative_position, item2.relative_position)
+    end
+
+    it 'uses rebalancing if there is no place' do
+      item1.update relative_position: 100
+      item2.update relative_position: 101
+      item3 = create_item(relative_position: 102)
+      new_item.update relative_position: 103
+
+      new_item.move_between(item2, item3)
+      new_item.save!
+
+      expect(new_item.relative_position).to be_between(item2.relative_position, item3.relative_position)
+      expect(item1.reload.relative_position).not_to eq(100)
+    end
+
+    it 'positions item right if we pass none-sequential parameters' do
+      item1.update relative_position: 99
+      item2.update relative_position: 101
+      item3 = create_item(relative_position: 102)
+      new_item.update relative_position: 103
+
+      new_item.move_between(item1, item3)
+      new_item.save!
+
+      expect(new_item.relative_position).to be(100)
+    end
+  end
+end