Filter excluded tags within the section map builder

Because we need might need excluded tags to build compare links, the
section map generator needs to have access to those tags. But, we don't
want excluded tags to have section headers. So instead, we'll create
another copy of the list that doesn't have tags excluded.

Signed-off-by: Tom Duffield <tom@chef.io>

spec/unit/generator/generator_tags_spec.rb

@@ -14,13 +14,21 @@ describe GitHubChangelogGenerator::Generator do
   end
 
   describe "#build_tag_section_mapping" do
-    let(:sorted_tags) { tags_from_strings(%w(8 7 6 5 4 3 2 1)) }
-    let(:filtered_tags) { generator.get_filtered_tags(sorted_tags) }
+    let(:all_tags) { tags_from_strings(%w(8 7 6 5 4 3 2 1)) }
+    let(:sorted_tags) { all_tags }
+
     let(:options) { {} }
     let(:generator) { GitHubChangelogGenerator::Generator.new(options) }
 
+    before do
+      allow_any_instance_of(GitHubChangelogGenerator::OctoFetcher).to receive(:get_all_tags).and_return(all_tags)
+      allow(generator).to receive(:fetch_tags_dates).with(all_tags)
+      allow(generator).to receive(:sort_tags_by_date).with(all_tags).and_return(sorted_tags)
+      generator.fetch_and_filter_tags
+    end
+
     subject do
-      generator.build_tag_section_mapping(filtered_tags, sorted_tags)
+      generator.tag_section_mapping
     end
 
     shared_examples_for "a section mapping" do
@@ -45,6 +53,20 @@ describe GitHubChangelogGenerator::Generator do
       it_behaves_like "a section mapping"
     end
 
+    shared_examples_for "a changelog with some exclusions" do
+      let(:expected_mapping) do
+        {
+          tag_with_name("8") => [tag_with_name("7"), tag_with_name("8")],
+          tag_with_name("6") => [tag_with_name("5"), tag_with_name("6")],
+          tag_with_name("4") => [tag_with_name("3"), tag_with_name("4")],
+          tag_with_name("3") => [tag_with_name("2"), tag_with_name("3")],
+          tag_with_name("1") => [nil, tag_with_name("1")]
+        }
+      end
+
+      it_behaves_like "a section mapping"
+    end
+
     context "with no constraints" do
       it_behaves_like "a full changelog"
     end
@@ -120,6 +142,26 @@ describe GitHubChangelogGenerator::Generator do
 
       it_behaves_like "a section mapping"
     end
+
+    context "with excluded tags" do
+      context "as a list of strings" do
+        let(:options) { { exclude_tags: %w(2 5 7) } }
+
+        it_behaves_like "a changelog with some exclusions"
+      end
+
+      context "as a regex" do
+        let(:options) { { exclude_tags: /[257]/ } }
+
+        it_behaves_like "a changelog with some exclusions"
+      end
+
+      context "as a regex string" do
+        let(:options) { { exclude_tags_regex: "[257]" } }
+
+        it_behaves_like "a changelog with some exclusions"
+      end
+    end
   end
 
   describe "#filter_between_tags" do