Refactor cycle analytics specs.

1. Generalise the specs that will be common across all cycle analytics
   phases.

2. Rewrite specs `issue` and `plan` to use this abstracted testing
   strategy.

3. Specs that are specific to a given phase, or unwieldy to test in an
   abstracted manner, are added to each phase's spec.

spec/models/cycle_analytics/issue_spec.rb

@@ -5,44 +5,14 @@ describe 'CycleAnalytics#issue', models: true do
   let(:from_date) { 10.days.ago }
   subject { CycleAnalytics.new(project, from: from_date) }
 
-  context "when a milestone is added to the issue" do
-    it "calculates the median of available durations (between issue creation and milestone addition)" do
-      time_differences = Array.new(5) do
-        start_time = Time.now
-        end_time = rand(1..10).days.from_now
-
-        milestone = create(:milestone, project: project)
-        issue = Timecop.freeze(start_time) { create(:issue, project: project) }
-        Timecop.freeze(end_time) { issue.update(milestone: milestone) }
-
-        end_time - start_time
-      end
-
-      median_time_difference = time_differences.sort[2]
-      expect(subject.issue).to eq(median_time_difference)
-    end
-  end
-
-  context "when a label is added to the issue" do
-    context "when the label is a list-label" do
-      it "calculates the median of available durations (between issue creation and label addition)" do
-        time_differences = Array.new(5) do
-          start_time = Time.now
-          end_time = rand(1..10).days.from_now
-
-          list_label = create(:label, lists: [create(:list)])
-          issue = Timecop.freeze(start_time) { create(:issue, project: project) }
-          Timecop.freeze(end_time) { issue.update(label_ids: [list_label.id]) }
-
-          end_time - start_time
-        end
-
-        median_time_difference = time_differences.sort[2]
-        expect(subject.issue).to eq(median_time_difference)
-      end
-    end
-
-    it "does not make a calculation for regular labels" do
+  generate_cycle_analytics_spec(phase: :issue,
+                                data_fn: -> (context) { { issue: context.build(:issue, project: context.project) } },
+                                start_time_conditions: [["issue created", -> (context, data) { data[:issue].save }]],
+                                end_time_conditions:   [["issue associated with a milestone", -> (context, data) { data[:issue].update(milestone: context.create(:milestone, project: context.project)) if data[:issue].persisted? }],
+                                                        ["list label added to issue", -> (context, data) { data[:issue].update(label_ids: [context.create(:label, lists: [context.create(:list)]).id]) if data[:issue].persisted? }]])
+
+  context "when a regular label (instead of a list label) is added to the issue" do
+    it "returns nil" do
       5.times do
         regular_label = create(:label)
         issue = create(:issue, project: project)
@@ -53,39 +23,14 @@ describe 'CycleAnalytics#issue', models: true do
     end
   end
 
-  context "when a milestone and list-label are both added to the issue" do
-    it "calculates the median of available durations (between issue creation and milestone addition)" do
-      start_time = Time.now
-      milestone_add_time = rand(1..10).days.from_now
-      list_label_add_time = rand(1..10).days.from_now
-
-      milestone = create(:milestone, project: project)
-      list_label = create(:label, lists: [create(:list)])
-      issue = Timecop.freeze(start_time) { create(:issue, project: project) }
-      Timecop.freeze(milestone_add_time) { issue.update(milestone: milestone) }
-      Timecop.freeze(list_label_add_time) { issue.update(label_ids: [list_label.id]) }
-
-      expect(subject.issue).to eq(milestone_add_time - start_time)
-    end
-
-    it "does not include issues from other projects" do
-      milestone = create(:milestone, project: project)
-      list_label = create(:label, lists: [create(:list)])
-      issue = create(:issue)
-      issue.update(milestone: milestone)
-      issue.update(label_ids: [list_label.id])
+  context "when the issue belongs to a different project" do
+    it 'returns nil' do
+      other_project = create(:project)
 
-      expect(subject.issue).to be_nil
-    end
-
-    it "excludes issues created before the 'from' date" do
-      before_from_date = from_date - 5.days
-
-      milestone = create(:milestone, project: project)
-      list_label = create(:label, lists: [create(:list)])
-      issue = Timecop.freeze(before_from_date) { create(:issue, project: project)}
-      issue.update(milestone: milestone)
-      issue.update(label_ids: [list_label.id])
+      5.times do
+        issue = create(:issue, project: other_project)
+        issue.update(milestone: create(:milestone, project: other_project))
+      end
 
       expect(subject.issue).to be_nil
     end

spec/models/cycle_analytics/plan_spec.rb

@@ -6,126 +6,38 @@ describe 'CycleAnalytics#plan', feature: true do
   let(:user) { create(:user, :admin) }
   subject { CycleAnalytics.new(project, from: from_date) }
 
-  def create_commit_referencing_issue(issue, time: Time.now)
-    sha = Timecop.freeze(time) { project.repository.commit_file(user, FFaker::Product.brand, "content", "Commit for ##{issue.iid}", "master", false) }
+  def create_commit_referencing_issue(issue)
+    sha = project.repository.commit_file(user, FFaker::Product.brand, "content", "Commit for ##{issue.iid}", "master", false)
     commit = project.repository.commit(sha)
     commit.create_cross_references!
   end
 
-  context "when a milestone is added to the issue" do
-    context "when the issue is mentioned in a commit" do
-      it "calculates the median of available durations between the two" do
-        time_differences = Array.new(5) do
-          start_time = Time.now
-          end_time = rand(1..10).days.from_now
+  generate_cycle_analytics_spec(phase: :plan,
+                                data_fn: -> (context) { { issue: context.create(:issue, project: context.project) } },
+                                start_time_conditions: [["issue associated with a milestone", -> (context, data) { data[:issue].update(milestone: context.create(:milestone, project: context.project)) }],
+                                                        ["list label added to issue", -> (context, data) { data[:issue].update(label_ids: [context.create(:label, lists: [context.create(:list)]).id]) }]],
+                                end_time_conditions:   [["issue mentioned in a commit", -> (context, data) { context.create_commit_referencing_issue(data[:issue]) }]])
 
-          milestone = create(:milestone, project: project)
-          issue = create(:issue, project: project)
+  context "when a regular label (instead of a list label) is added to the issue" do
+    it "returns nil" do
+      label = create(:label)
+      issue = create(:issue, project: project)
+      issue.update(label_ids: [label.id])
+      create_commit_referencing_issue(issue)
 
-          Timecop.freeze(start_time) { issue.update(milestone: milestone) }
-          create_commit_referencing_issue(issue, time: end_time)
-
-          end_time - start_time
-        end
-
-        median_time_difference = time_differences.sort[2]
-
-        # Use `be_within` to account for time lost between Rails invoking CLI git
-        # and the commit being created, which Timecop can't freeze.
-        expect(subject.plan).to be_within(2).of(median_time_difference)
-      end
-    end
-  end
-
-  context "when a label is added to the issue" do
-    context "when the issue is mentioned in a commit" do
-      context "when the label is a list-label" do
-        it "calculates the median of available durations between the two" do
-          time_differences = Array.new(5) do
-            start_time = Time.now
-            end_time = rand(1..10).days.from_now
-
-            issue = create(:issue, project: project)
-            list_label = create(:label, lists: [create(:list)])
-
-            Timecop.freeze(start_time) { issue.update(label_ids: [list_label.id]) }
-            create_commit_referencing_issue(issue, time: end_time)
-
-            end_time - start_time
-          end
-
-          median_time_difference = time_differences.sort[2]
-
-          # Use `be_within` to account for time lost between Rails invoking CLI git
-          # and the commit being created, which Timecop can't freeze.
-          expect(subject.plan).to be_within(2).of(median_time_difference)
-        end
-      end
-
-      it "does not make a calculation for regular labels" do
-        5.times do
-          regular_label = create(:label)
-          issue = create(:issue, project: project)
-          issue.update(label_ids: [regular_label.id])
-
-          create_commit_referencing_issue(issue)
-        end
-
-        expect(subject.plan).to be_nil
-      end
+      expect(subject.issue).to be_nil
     end
   end
 
-  context "when a milestone and list-label are both added to the issue" do
-    context "when the issue is mentioned in a commit" do
-      it "calculates the median of available durations between the two (using milestone addition as the 'start_time')" do
-        time_differences = Array.new(5) do
-          label_addition_time = Time.now
-          milestone_addition_time = rand(2..12).hours.from_now
-          end_time = rand(1..10).days.from_now
-
-          issue = create(:issue, project: project)
-          milestone = create(:milestone, project: project)
-          list_label = create(:label, lists: [create(:list)])
-
-          Timecop.freeze(label_addition_time) { issue.update(label_ids: [list_label.id]) }
-          Timecop.freeze(milestone_addition_time) { issue.update(milestone: milestone) }
-          create_commit_referencing_issue(issue, time: end_time)
-
-          end_time - milestone_addition_time
-        end
-
-        median_time_difference = time_differences.sort[2]
+  it "does not include issues from other projects" do
+    other_project = create(:project)
 
-        # Use `be_within` to account for time lost between Rails invoking CLI git
-        # and the commit being created, which Timecop can't freeze.
-        expect(subject.plan).to be_within(2).of(median_time_difference)
-      end
+    list_label = create(:label, lists: [create(:list)])
+    issue = create(:issue, project: other_project)
+    issue.update(milestone: create(:milestone))
+    issue.update(label_ids: [list_label.id])
+    create_commit_referencing_issue(issue)
 
-      it "does not include issues from other projects" do
-        other_project = create(:project)
-
-        list_label = create(:label, lists: [create(:list)])
-        issue = create(:issue, project: other_project)
-        issue.update(milestone: create(:milestone))
-        issue.update(label_ids: [list_label.id])
-        create_commit_referencing_issue(issue)
-
-        expect(subject.issue).to be_nil
-      end
-
-      it "excludes issues created before the 'from' date" do
-        before_from_date = from_date - 5.days
-
-        milestone = create(:milestone, project: project)
-        list_label = create(:label, lists: [create(:list)])
-        issue = Timecop.freeze(before_from_date) { create(:issue, project: project)}
-        issue.update(milestone: milestone)
-        issue.update(label_ids: [list_label.id])
-        create_commit_referencing_issue(issue)
-
-        expect(subject.issue).to be_nil
-      end
-    end
+    expect(subject.issue).to be_nil
   end
 end

spec/support/cycle_analytics_helpers.rb

+# rubocop:disable Metrics/AbcSize
+
+# Note: The ABC size is large here because we have a method generating test cases with
+#       multiple nested contexts. This shouldn't count as a violation.
+
+module CycleAnalyticsHelpers
+  # Generate the most common set of specs that all cycle analytics phases need to have.
+  #
+  # Arguments:
+  #
+  #                  phase: Which phase are we testing? Will call `CycleAnalytics.new.send(phase)` for the final assertion
+  #                data_fn: A function that returns a hash, constituting initial data for the test case
+  #  start_time_conditions: An array of `conditions`. Each condition is an tuple of `condition_name` and `condition_fn`. `condition_fn` is called with
+  #                         `context` (no lexical scope, so need to do `context.create` for factories, for example) and `data` (from the `data_fn`).
+  #                         Each `condition_fn` is expected to implement a case which consitutes the start of the given cycle analytics phase.
+  #    end_time_conditions: An array of `conditions`. Each condition is an tuple of `condition_name` and `condition_fn`. `condition_fn` is called with
+  #                         `context` (no lexical scope, so need to do `context.create` for factories, for example) and `data` (from the `data_fn`).
+  #                         Each `condition_fn` is expected to implement a case which consitutes the end of the given cycle analytics phase.
+
+  def generate_cycle_analytics_spec(phase:, data_fn:, start_time_conditions:, end_time_conditions:)
+    combinations_of_start_time_conditions = (1..start_time_conditions.size).flat_map { |size| start_time_conditions.combination(size).to_a }
+    combinations_of_end_time_conditions = (1..end_time_conditions.size).flat_map { |size| end_time_conditions.combination(size).to_a }
+
+    scenarios = combinations_of_start_time_conditions.product(combinations_of_end_time_conditions)
+    scenarios.each do |start_time_conditions, end_time_conditions|
+      context "start condition: #{start_time_conditions.map(&:first).to_sentence}" do
+        context "end condition: #{end_time_conditions.map(&:first).to_sentence}" do
+          it "finds the median of available durations between the two conditions" do
+            time_differences = Array.new(5) do
+              data = data_fn[self]
+              start_time = Time.now
+              end_time = rand(1..10).days.from_now
+
+              start_time_conditions.each do |condition_name, condition_fn|
+                Timecop.freeze(start_time) { condition_fn[self, data] }
+              end
+
+              end_time_conditions.each do |condition_name, condition_fn|
+                Timecop.freeze(end_time) { condition_fn[self, data] }
+              end
+
+              end_time - start_time
+            end
+
+            median_time_difference = time_differences.sort[2]
+            expect(subject.send(phase)).to be_within(2).of(median_time_difference)
+          end
+        end
+      end
+
+      context "start condition NOT PRESENT: #{start_time_conditions.map(&:first).to_sentence}" do
+        context "end condition: #{end_time_conditions.map(&:first).to_sentence}" do
+          it "returns nil" do
+            5.times do
+              data = data_fn[self]
+              end_time = rand(1..10).days.from_now
+
+              end_time_conditions.each_with_index do |(condition_name, condition_fn), index|
+                Timecop.freeze(end_time + index.days) { condition_fn[self, data] }
+              end
+            end
+
+            expect(subject.send(phase)).to be_nil
+          end
+        end
+      end
+
+      context "start condition: #{start_time_conditions.map(&:first).to_sentence}" do
+        context "end condition NOT PRESENT: #{end_time_conditions.map(&:first).to_sentence}" do
+          it "returns nil" do
+            5.times do
+              data = data_fn[self]
+              start_time = Time.now
+
+              start_time_conditions.each do |condition_name, condition_fn|
+                Timecop.freeze(start_time) { condition_fn[self, data] }
+              end
+            end
+
+            expect(subject.send(phase)).to be_nil
+          end
+        end
+      end
+    end
+
+    context "when none of the start / end conditions are matched" do
+      it "returns nil" do
+        expect(subject.send(phase)).to be_nil
+      end
+    end
+  end
+end
+
+RSpec.configure do |config|
+  config.extend CycleAnalyticsHelpers
+end