Generate license text when missing for detected license

lib/licensed/dependency.rb

@@ -72,9 +72,12 @@ def license_key
     # Returns the license text content from all matched sources
     # except the package file, which doesn't contain license text.
     def license_contents
-      matched_files.reject { |f| f == package_file }
-                   .group_by(&:content)
-                   .map { |content, files| { "sources" => license_content_sources(files), "text" => content } }
+      files = matched_files.reject { |f| f == package_file }
+                           .group_by(&:content)
+                           .map { |content, files| { "sources" => license_content_sources(files), "text" => content } }
+
+      files << generated_license_contents if files.empty?
+      files.compact
     end
 
     # Returns legal notices found at the dependency path
@@ -133,5 +136,25 @@ def license_metadata
         "license" => license_key
       })
     end
+
+    # Returns a generated license content source and text for the dependency's
+    # license if it exists and is not "other"
+    def generated_license_contents
+      return unless license
+      return if license.key == "other"
+
+      # strip copyright clauses and any extra newlines
+      # many package managers don't provide enough information to
+      # autogenerate a copyright clause
+      text = license.text.lines
+                         .reject { |l| l =~ Licensee::Matchers::Copyright::REGEX }
+                         .join
+                         .gsub(/\n\n\n/, "\n\n")
+
+      {
+        "sources" => "Auto-generated #{license.spdx_id} license text",
+        "text" => text
+      }
+    end
   end
 end

test/dependency_test.rb

@@ -123,13 +123,49 @@ def mkproject(&block)
       end
     end
 
-    it "does not get license content from package manager file" do
+    it "autogenerates license content if explicit content is not found" do
       mkproject do |dependency|
         File.write "project.gemspec", "s.license = 'mit'"
+
+        contents = dependency.license_contents.first
+        assert contents
+        assert_match /auto-generated/i, contents["sources"]
+        refute_match /copyright \(c\)/i, contents["text"]
+
+        file = Licensee::ProjectFiles::LicenseFile.new(contents["text"])
+        assert_equal "mit", file.license&.key
+      end
+    end
+
+    it "does not autogenerate license content for 'other' license key" do
+      mkproject do |dependency|
+        File.write "project.gemspec", "s.license = 'other'"
+
         assert_empty dependency.license_contents
       end
     end
 
+    it "does not autogenerate license content for licenses unknown to Licensee" do
+      mkproject do |dependency|
+        File.write "project.gemspec", "s.license = 'nit'"
+
+        assert_empty dependency.license_contents
+      end
+    end
+
+    it "does not autogenerate license content if license is not found" do
+      mkproject do |dependency|
+        assert_empty dependency.license_contents
+      end
+    end
+
+    it "does not autogenerate license content if explicit content is set" do
+      mkproject do |dependency|
+        File.write "LICENSE", Licensee::License.find("mit").text
+        refute dependency.license_contents.any? { |c| c["sources"] =~ /auto-generated/i }
+      end
+    end
+
     it "gets license from readme" do
       mkproject do |dependency|
         File.write "README.md", "# License\n" + Licensee::License.find("mit").text