Fix collection option related issue

We have recently added support to provide collection options either
as an command line arguments or options in the collection file. But
that is only working on the site interface, and the collection cli
still expect the `output-folder` as required option.

This commit changes that, so it's not required anymore and it will
try to read the option from the file, and if none of those source
has this value, then it will use the source as output directory.

Fixes #283

lib/metanorma/cli/collection.rb

@@ -26,11 +26,15 @@ def collection_file
         @collection_file ||= Metanorma::Collection.parse(file)
       end
 
+      def source_folder
+        @source_folder ||= File.dirname(File.expand_path(file))
+      end
+
       def collection_options
-        {
+        @collection_options ||= {
           compile: @compile_options,
           coverpage: options.fetch(:coverpage, nil),
-          output_folder: options.fetch(:output_folder, nil),
+          output_folder: options.fetch(:output_folder, source_folder),
           format: collection_output_formats(options.fetch(:format, "")),
         }
       end

lib/metanorma/cli/command.rb

@@ -59,7 +59,7 @@ def compile(file_name = nil)
 
       desc "collection FILENAME", "Render HTML pages from XML/YAML colection"
       option :format, aliases: "-x", type: :string, desc: "Formats to generate"
-      option :output_folder, aliases: "-w", required: true, desc: "Directory to save compiled files"
+      option :output_folder, aliases: "-w", desc: "Directory to save compiled files"
       option :coverpage, aliases: "-c", desc: "Liquid template"
       option :agree_to_terms, type: :boolean, desc: "Agree / Disagree with all third-party licensing terms "\
                                                     "presented (WARNING: do know what you are agreeing with!)"

spec/metanorma/cli/collection_spec.rb

@@ -5,9 +5,16 @@
     context "with specified options" do
       it "compiles and renders the collection files" do
         collection = mock_collection_instance
-        Metanorma::Cli::Collection.render(collection_file, format: "html, pdf")
 
-        expect(collection).to have_received(:render).with(format: %I(html pdf))
+        Metanorma::Cli::Collection.render(
+          collection_file,
+          format: "html, pdf",
+          output_folder: "bilingual-brochure",
+        )
+
+        expect(collection).to have_received(:render).with(
+          format: %I(html pdf), output_folder: "bilingual-brochure",
+        )
       end
     end
 
@@ -25,6 +32,18 @@
         )
       end
     end
+
+    context "with missing options" do
+      it "usages the source as reference for options" do
+        collection = mock_collection_instance
+
+        Metanorma::Cli::Collection.render(collection_file)
+
+        expect(collection).to have_received(:render).with(
+          hash_including(output_folder: File.dirname(collection_file.to_s)),
+        )
+      end
+    end
   end
 
   def collection_file(collection = "collection1.yml")