Refactor specs to separate concerns.

lib/gitlab/database/count.rb

@@ -25,7 +25,7 @@ module Gitlab
       #
       # @param [Array]
       # @return [Hash] of Model -> count mapping
-      def self.approximate_counts(models, strategies = [ReltuplesCountStrategy, ExactCountStrategy])
+      def self.approximate_counts(models, strategies: [ReltuplesCountStrategy, ExactCountStrategy])
         strategies.each_with_object({}) do |strategy, counts_by_model|
           if strategy.enabled?
             models_with_missing_counts = models - counts_by_model.keys
@@ -38,14 +38,6 @@ module Gitlab
         end
       end
 
-      # Returns a hash of the table names that have recently updated tuples.
-      #
-      # @param [Array] models to count
-      # @returns [Hash] Table name to count mapping (e.g. { 'projects' => 5, 'users' => 100 })
-      def self.reltuples_from_recently_updated(models)
-        ReltuplesCountStrategy.new(models).count
-      end
-
       class ExactCountStrategy
         attr_reader :models
         def initialize(models)

spec/lib/gitlab/database/count_spec.rb

@@ -7,28 +7,29 @@ describe Gitlab::Database::Count do
   end
 
   let(:models) { [Project, Identity] }
+  let(:reltuples_strategy) { double('reltuples_strategy', count: {}) }
+  let(:exact_strategy) { double('exact_strategy', count: {}) }
 
-  describe '.approximate_counts' do
-    context 'with MySQL' do
-      context 'when reltuples have not been updated' do
-        it 'counts all models the normal way' do
-          expect(Gitlab::Database).to receive(:postgresql?).and_return(false)
+  before do
+    allow(Gitlab::Database::Count::ReltuplesCountStrategy).to receive(:new).with(models).and_return(reltuples_strategy)
+  end
 
-          expect(Project).to receive(:count).and_call_original
-          expect(Identity).to receive(:count).and_call_original
+  context '.approximate_counts' do
+    context 'selecting strategies' do
+      let(:strategies) { [double('s1', :enabled? => true), double('s2', :enabled? => false)] }
 
-          expect(described_class.approximate_counts(models)).to eq({ Project => 3, Identity => 1 })
-        end
+      it 'uses only enabled strategies' do
+        expect(strategies[0]).to receive(:new).and_return(double('strategy1', count: {}))
+        expect(strategies[1]).not_to receive(:new)
+
+        described_class.approximate_counts(models, strategies: strategies)
       end
     end
 
-    context 'with PostgreSQL', :postgresql do
-      let(:reltuples_strategy) { double('reltuples_strategy', count: {}) }
-
-      before do
-        allow(Gitlab::Database::Count::ReltuplesCountStrategy).to receive(:new).with(models).and_return(reltuples_strategy)
+    context 'fallbacks' do
     end
 
+    context 'with PostgreSQL', :postgresql do
       describe 'when reltuples have not been updated' do
         it 'counts all models the normal way' do
           expect(Project).to receive(:count).and_call_original
@@ -77,12 +78,56 @@ describe Gitlab::Database::Count do
       describe Gitlab::Database::Count::ExactCountStrategy do
         subject { described_class.new(models).count }
 
+        describe '#count' do
           it 'counts all models' do
             models.each { |model| expect(model).to receive(:count).and_call_original }
 
             expect(subject).to eq({ Project => 3, Identity => 1 })
           end
         end
+
+        describe '.enabled?' do
+          it 'is enabled for PostgreSQL' do
+            allow(Gitlab::Database).to receive(:postgresql?).and_return(true)
+
+            expect(described_class.enabled?).to be_truthy
+          end
+
+          it 'is enabled for MySQL' do
+            allow(Gitlab::Database).to receive(:postgresql?).and_return(false)
+
+            expect(described_class.enabled?).to be_truthy
+          end
+        end
+      end
+
+      describe Gitlab::Database::Count::ReltuplesCountStrategy do
+        subject { described_class.new(models).count }
+
+        describe '#count' do
+          context 'when reltuples is not up to date' do
+            it 'returns an empty hash' do
+              models.each { |model| expect(model).not_to receive(:count) }
+
+              expect(subject).to eq({})
+            end
+          end
+        end
+
+        describe '.enabled?' do
+          it 'is enabled for PostgreSQL' do
+            allow(Gitlab::Database).to receive(:postgresql?).and_return(true)
+
+            expect(described_class.enabled?).to be_truthy
+          end
+
+          it 'is disabled for MySQL' do
+            allow(Gitlab::Database).to receive(:postgresql?).and_return(false)
+
+            expect(described_class.enabled?).to be_falsey
+          end
+        end
+      end
     end
   end
 end