Add --[no-]use-lcs

Add a CLI option (--[no-]use-lcs) so the usage of the LCS algo when
comparing arrays can be switched on and off. The default is to keep it
on as it's has been so far.

Closes #207

Author: nbarrientos

doc/optionsref.md

@@ -72,6 +72,7 @@ Usage: octocatalog-diff [command line options]
         --from-enc PATH              Path to ENC script (for the from catalog only)
         --to-enc PATH                Path to ENC script (for the to catalog only)
         --[no-]display-detail-add    Display parameters and other details for added resources
+        --[no-]use-lcs               Use the LCS algorithm to determine differences in arrays
         --[no-]truncate-details      Truncate details with --display-detail-add
         --no-header                  Do not print a header
         --default-header             Print default header with output

lib/octocatalog-diff/catalog-diff/differ.rb

@@ -531,9 +531,11 @@ def hashdiff_initial(catalog1_in, catalog2_in)
         catalog2_resources = catalog2_in[:catalog]
 
         @logger.debug "Entering hashdiff_initial; catalog sizes: #{catalog1_resources.size}, #{catalog2_resources.size}"
+        use_lcs = @opts.fetch(:use_lcs, true)
+        @logger.debug "HashDiff configuration: (use_lcs: #{use_lcs})"
         result = []
         hashdiff_add_remove = Set.new
-        hashdiff_result = HashDiff.diff(catalog1_resources, catalog2_resources, delimiter: "\f")
+        hashdiff_result = HashDiff.diff(catalog1_resources, catalog2_resources, delimiter: "\f", use_lcs: use_lcs)
         hashdiff_result.each do |obj|
           # Regular change
           if obj[0] == '~'

lib/octocatalog-diff/cli.rb

@@ -44,7 +44,8 @@ class Cli
       display_datatype_changes: true,
       parallel: true,
       suppress_absent_file_details: true,
-      hiera_path: 'hieradata'
+      hiera_path: 'hieradata',
+      use_lcs: true
     }.freeze
 
     # This method is the one to call externally. It is possible to specify alternate

lib/octocatalog-diff/cli/options/use_lcs.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Configures using the Longest common subsequence (LCS) algorithm to determine differences in arrays
+# @param parser [OptionParser object] The OptionParser argument
+# @param options [Hash] Options hash being constructed; this is modified in this method.
+OctocatalogDiff::Cli::Options::Option.newoption(:use_lcs) do
+  has_weight 250
+
+  def parse(parser, options)
+    parser.on('--[no-]use-lcs', 'Use the LCS algorithm to determine differences in arrays') do |x|
+      options[:use_lcs] = x
+    end
+  end
+end

spec/octocatalog-diff/tests/catalog-diff/differ_spec.rb

@@ -1544,5 +1544,55 @@
         end
       end
     end
+
+    context 'use_lcs is taken into account' do
+      describe '#ignore' do
+        before(:all) do
+          r1 = [
+            {
+              'type' => 'Example1', 'title' => 'main', 'tags' => ['stage'], 'exported' => false,
+              'parameters' => {
+                'name' => 'main', 'toplevel' => 'toplevel attribute',
+                'nest' => {
+                  'toplevel' => 'toplevel_nest attribute',
+                  'nest' => { 'nest' => 'nested nested text' },
+                  'nest2' => { 'chicken' => 'egg' },
+                  'chicken' => 'egg'
+                }
+              }
+            }
+          ]
+          @c1 = OctocatalogDiff::Spec.build_catalog(r1)
+          @c2 = OctocatalogDiff::Spec.build_catalog(r1)
+        end
+
+        it 'should honor the algo configuration passed in the options (false)' do
+          logger, logger_str = OctocatalogDiff::Spec.setup_logger
+          opts = { use_lcs: false, logger: logger }
+          testobj = OctocatalogDiff::CatalogDiff::Differ.new(opts, @c1, @c2)
+          testobj.diff
+          expect(logger_str.string).to match(/Entering hashdiff_initial; catalog sizes: 1, 1/)
+          expect(logger_str.string).to match(/HashDiff configuration: \(use_lcs: false\)/)
+        end
+
+        it 'should honor the algo configuration passed in the options (true)' do
+          logger, logger_str = OctocatalogDiff::Spec.setup_logger
+          opts = { use_lcs: true, logger: logger }
+          testobj = OctocatalogDiff::CatalogDiff::Differ.new(opts, @c1, @c2)
+          testobj.diff
+          expect(logger_str.string).to match(/Entering hashdiff_initial; catalog sizes: 1, 1/)
+          expect(logger_str.string).to match(/HashDiff configuration: \(use_lcs: true\)/)
+        end
+
+        it 'the default value is true' do
+          logger, logger_str = OctocatalogDiff::Spec.setup_logger
+          opts = { logger: logger }
+          testobj = OctocatalogDiff::CatalogDiff::Differ.new(opts, @c1, @c2)
+          testobj.diff
+          expect(logger_str.string).to match(/Entering hashdiff_initial; catalog sizes: 1, 1/)
+          expect(logger_str.string).to match(/HashDiff configuration: \(use_lcs: true\)/)
+        end
+      end
+    end
   end
 end

spec/octocatalog-diff/tests/cli/options/use_lcs_spec.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require_relative '../options_helper'
+
+describe OctocatalogDiff::Cli::Options do
+  describe '#opt_use_lcs' do
+    include_examples 'true/false option', 'use-lcs', :use_lcs
+  end
+end

spec/octocatalog-diff/tests/cli_spec.rb

@@ -37,7 +37,8 @@
           display_datatype_changes: true,
           parallel: true,
           suppress_absent_file_details: true,
-          hiera_path: 'hieradata'
+          hiera_path: 'hieradata',
+          use_lcs: true
         }
         logger, _logger_str = OctocatalogDiff::Spec.setup_logger
         expect(described_class).to receive(:catalog_only).with(logger, answer)