Atomic generation of internal ids for issues.

2 files changed, 93 insertions, 0 deletions

diff --git a/spec/factories/internal_ids.rb b/spec/factories/internal_ids.rb
new file mode 100644
index 00000000000..b4c14d22a29
--- /dev/null
+++ b/spec/factories/internal_ids.rb
@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :internal_id do
+    project
+    usage { InternalId.usages.keys.first }
+  end
+end
diff --git a/spec/models/internal_id_spec.rb b/spec/models/internal_id_spec.rb
new file mode 100644
index 00000000000..b953b6a2df8
--- /dev/null
+++ b/spec/models/internal_id_spec.rb
@@ -0,0 +1,87 @@
+require 'spec_helper'
+
+describe InternalId do
+  let(:project) { create(:project) }
+  let(:usage) { :issues }
+
+  context 'validations' do
+    it { is_expected.to validate_presence_of(:usage) }
+    it { is_expected.to validate_presence_of(:project_id) }
+  end
+
+  describe '.generate_next' do
+    context 'in the absence of a record' do
+      subject { described_class.generate_next(project, usage) }
+
+      it 'creates a record if not yet present' do
+        expect { subject }.to change { described_class.count }.from(0).to(1)
+      end
+
+      it 'stores record attributes' do
+        subject
+
+        described_class.first.tap do |record|
+          expect(record.project).to eq(project)
+          expect(record.usage).to eq(usage.to_s) # TODO
+        end
+      end
+
+      context 'with existing issues' do
+        before do
+          rand(10).times { create(:issue, project: project) }
+        end
+
+        it 'calculates last_value values automatically' do
+          expect(subject).to eq(project.issues.size + 1)
+        end
+      end
+    end
+
+    it 'generates a strictly monotone, gapless sequence' do
+      seq = (0..rand(1000)).map do
+        described_class.generate_next(project, usage)
+      end
+      normalized = seq.map { |i| i - seq.min }
+      expect(normalized).to eq((0..seq.size - 1).to_a)
+    end
+  end
+
+  describe '#increment_and_save!' do
+    let(:id) { create(:internal_id) }
+    subject { id.increment_and_save! }
+
+    it 'returns incremented iid' do
+      value = id.last_value
+      expect(subject).to eq(value + 1)
+    end
+
+    it 'saves the record' do
+      subject
+      expect(id.changed?).to be_falsey
+    end
+
+    context 'with last_value=nil' do
+      let(:id) { build(:internal_id, last_value: nil) }
+
+      it 'returns 1' do
+        expect(subject).to eq(1)
+      end
+    end
+  end
+
+  describe '#calculate_last_value! (for issues)' do
+    subject do
+      build(:internal_id, project: project, usage: :issues)
+    end
+
+    context 'with existing issues' do
+      before do
+        rand(10).times { create(:issue, project: project) }
+      end
+
+      it 'counts related issues and saves' do
+        expect { subject.calculate_last_value! }.to change { subject.last_value }.from(nil).to(project.issues.size)
+      end
+    end
+  end
+end