Better support around bundler changelogs (#9429)

* Support bundler changelogs that use a version in their changelog url

* Add tests for when the changelog source points to a file or directory

* Assign and return in one line

common/lib/dependabot/metadata_finders/base/changelog_finder.rb

@@ -128,6 +128,15 @@ def changelog_from_suggested_url
           tmp_files = T.unsafe(suggested_source_client).contents(suggested_source&.repo, opts)
 
           filename = T.must(T.must(suggested_changelog_url).split("/").last).split("#").first
+
+          # If the suggested source points to a specific directory
+          # then we will receive a hash for just the changelog file
+          if suggested_source&.directory && tmp_files[:name] == filename
+            return @changelog_from_suggested_url = tmp_files
+          end
+
+          # Otherwise we will get back an array of hashes representing the files
+          # in the root directory and we need to find the changelog
           @changelog_from_suggested_url =
             tmp_files.find { |f| f.name == filename }
         rescue Octokit::NotFound, Octokit::UnavailableForLegalReasons

common/spec/dependabot/metadata_finders/base/changelog_finder_spec.rb

@@ -157,6 +157,14 @@
         end
 
         context "when given a suggested_changelog_url" do
+          let(:suggested_changelog_url) do
+            "github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
+          end
+
+          let(:source) do
+            Dependabot::Source.from_url(suggested_changelog_url)
+          end
+
           let(:finder) do
             described_class.new(
               source: source,
@@ -165,44 +173,72 @@
               suggested_changelog_url: suggested_changelog_url
             )
           end
-          let(:suggested_changelog_url) do
-            "github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
-          end
 
-          before do
-            suggested_github_response =
-              fixture("github", "contents_sidekiq.json")
-            suggested_github_url =
-              "https://api.github.com/repos/mperham/sidekiq/contents/"
-            stub_request(:get, suggested_github_url)
-              .to_return(status: 200,
-                         body: suggested_github_response,
-                         headers: { "Content-Type" => "application/json" })
-          end
+          context "and it points to a specific directory" do
+            let(:suggested_changelog_url) do
+              "github.com/mperham/sidekiq/blob/master/dir/Pro-Changes.md"
+            end
 
-          it "gets the right URL" do
-            expect(subject)
-              .to eq(
-                "https://github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
-              )
+            before do
+              sidekiq_changelog =
+                fixture("github", "contents_sidekiq_changelog.json")
+              suggested_github_url =
+                "https://api.github.com/repos/mperham/sidekiq/contents/dir?ref=master"
+              stub_request(:get, suggested_github_url)
+                .to_return(status: 200,
+                           body: sidekiq_changelog,
+                           headers: { "Content-Type" => "application/json" })
+            end
+
+            it "gets the right URL" do
+              expect(subject)
+                .to eq(
+                  "https://github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
+                )
+            end
           end
 
-          context "that can't be found" do
+          context "but it does not point to a specific directory" do
+            let(:suggested_changelog_url) do
+              "github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
+            end
+
             before do
+              suggested_github_response =
+                fixture("github", "contents_sidekiq.json")
               suggested_github_url =
                 "https://api.github.com/repos/mperham/sidekiq/contents/"
               stub_request(:get, suggested_github_url)
-                .to_return(status: 404)
+                .to_return(status: 200,
+                           body: suggested_github_response,
+                           headers: { "Content-Type" => "application/json" })
             end
 
-            it "falls back to looking for the changelog as usual" do
+            it "gets the right URL" do
               expect(subject)
                 .to eq(
-                  "https://github.com/gocardless/business/" \
-                  "blob/master/CHANGELOG.md"
+                  "https://github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
                 )
             end
           end
+
+          context "that can't be found" do
+            before do
+              suggested_github_url =
+                "https://api.github.com/repos/mperham/sidekiq/contents/"
+              stub_request(:get, suggested_github_url)
+                .to_return(status: 404)
+
+              suggested_github_url_with_tag =
+                "https://api.github.com/repos/mperham/sidekiq/contents/?ref=v1.4.0"
+              stub_request(:get, suggested_github_url_with_tag)
+                .to_return(status: 404)
+            end
+
+            it "returns nil for the changelog url" do
+              expect(subject).to eq(nil)
+            end
+          end
         end
       end
 

common/spec/fixtures/github/contents_sidekiq_changelog.json

@@ -0,0 +1,16 @@
+{
+  "name": "Pro-Changes.md",
+  "path": "Pro-Changes.md",
+  "sha": "0c50ae70b0d731329c7be800f9e25fd1434ae0c9",
+  "size": 20276,
+  "url": "https://api.github.com/repos/mperham/sidekiq/contents/Pro-Changes.md?ref=master",
+  "html_url": "https://github.com/mperham/sidekiq/blob/master/Pro-Changes.md",
+  "git_url": "https://api.github.com/repos/mperham/sidekiq/git/blobs/0c50ae70b0d731329c7be800f9e25fd1434ae0c9",
+  "download_url": "https://raw.githubusercontent.com/mperham/sidekiq/master/Pro-Changes.md",
+  "type": "file",
+  "_links": {
+    "self": "https://api.github.com/repos/mperham/sidekiq/contents/Pro-Changes.md?ref=master",
+    "git": "https://api.github.com/repos/mperham/sidekiq/git/blobs/0c50ae70b0d731329c7be800f9e25fd1434ae0c9",
+    "html": "https://github.com/mperham/sidekiq/blob/master/Pro-Changes.md"
+  }
+}