Consolidate all cycle analytics helper methods.

1. Move the test generation to `CycleAnalyticsHelpers::TestGeneration`

2. Move all helper methods (previously placed in each individual spec
   file) to `CycleAnalyticsHelpers`

1 files changed, 154 insertions, 0 deletions

diff --git a/spec/support/cycle_analytics_helpers/test_generation.rb b/spec/support/cycle_analytics_helpers/test_generation.rb
new file mode 100644
index 00000000000..4e386691d78
--- /dev/null
+++ b/spec/support/cycle_analytics_helpers/test_generation.rb
@@ -0,0 +1,154 @@
+# 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
+  module TestGeneration
+    # 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.
+    #          before_end_fn: This function is run before calling the end time conditions. Used for setup that needs to be run between the start and end conditions.
+
+    def generate_cycle_analytics_spec(phase:, data_fn:, start_time_conditions:, end_time_conditions:, before_end_fn: nil)
+      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 |index|
+                data = data_fn[self]
+                start_time = (index * 10).days.from_now
+                end_time = start_time + rand(1..5).days
+
+                start_time_conditions.each do |condition_name, condition_fn|
+                  Timecop.freeze(start_time) { condition_fn[self, data] }
+                end
+
+                # Run `before_end_fn` at the midpoint between `start_time` and `end_time`
+                Timecop.freeze(start_time + (end_time - start_time)/2) { before_end_fn[self, data] } if before_end_fn
+
+                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(5).of(median_time_difference)
+            end
+
+            context "when the data belongs to another project" do
+              let(:other_project) { create(:project) }
+
+              it "returns nil" do
+                # Use a stub to "trick" the data/condition functions
+                # into using another project. This saves us from having to
+                # define separate data/condition functions for this particular
+                # test case.
+                allow(self).to receive(:project) { other_project }
+
+                5.times 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
+
+                # Turn off the stub before checking assertions
+                allow(self).to receive(:project).and_call_original
+
+                expect(subject.send(phase)).to be_nil
+              end
+            end
+
+            context "when the end condition happens before the start condition" do
+              it 'returns nil' do
+                data = data_fn[self]
+                start_time = Time.now
+                end_time = start_time + rand(1..5).days
+
+                # Run `before_end_fn` at the midpoint between `start_time` and `end_time`
+                Timecop.freeze(start_time + (end_time - start_time)/2) { before_end_fn[self, data] } if before_end_fn
+
+                end_time_conditions.each do |condition_name, condition_fn|
+                  Timecop.freeze(start_time) { condition_fn[self, data] }
+                end
+
+                start_time_conditions.each do |condition_name, condition_fn|
+                  Timecop.freeze(end_time) { condition_fn[self, data] }
+                end
+
+                expect(subject.send(phase)).to be_nil
+              end
+            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
+end
+
+RSpec.configure do |config|
+  config.extend CycleAnalyticsHelpers::TestGeneration
+end