Display slash commands outcome when previewing Markdown

Remove slash commands from Markdown preview and display their outcome next to
the text field.
Introduce new "explanation" block to our slash commands DSL.
Introduce optional "parse_params" block to slash commands DSL that allows to
process a parameter before it is passed to "explanation" or "command" blocks.
Pass path for previewing Markdown as "data" attribute instead of setting
a variable on "window".

2 files changed, 101 insertions, 17 deletions

diff --git a/spec/lib/gitlab/slash_commands/command_definition_spec.rb b/spec/lib/gitlab/slash_commands/command_definition_spec.rb
index c9c2f314e57..5b9173d3d3f 100644
--- a/spec/lib/gitlab/slash_commands/command_definition_spec.rb
+++ b/spec/lib/gitlab/slash_commands/command_definition_spec.rb
@@ -167,6 +167,58 @@ describe Gitlab::SlashCommands::CommandDefinition do
             end
           end
         end
+
+        context 'when the command defines parse_params block' do
+          before do
+            subject.parse_params_block = ->(raw) { raw.strip }
+            subject.action_block = ->(parsed) { self.received_arg = parsed }
+          end
+
+          it 'executes the command passing the parsed param' do
+            subject.execute(context, {}, 'something   ')
+
+            expect(context.received_arg).to eq('something')
+          end
+        end
+      end
+    end
+  end
+
+  describe '#explain' do
+    context 'when the command is not available' do
+      before do
+        subject.condition_block = proc { false }
+        subject.explanation = 'Explanation'
+      end
+
+      it 'returns nil' do
+        result = subject.explain({}, {}, nil)
+
+        expect(result).to be_nil
+      end
+    end
+
+    context 'when the explanation is a static string' do
+      before do
+        subject.explanation = 'Explanation'
+      end
+
+      it 'returns this static string' do
+        result = subject.explain({}, {}, nil)
+
+        expect(result).to eq 'Explanation'
+      end
+    end
+
+    context 'when the explanation is dynamic' do
+      before do
+        subject.explanation = proc { |arg| "Dynamic #{arg}" }
+      end
+
+      it 'invokes the proc' do
+        result = subject.explain({}, {}, 'explanation')
+
+        expect(result).to eq 'Dynamic explanation'
       end
     end
   end
diff --git a/spec/lib/gitlab/slash_commands/dsl_spec.rb b/spec/lib/gitlab/slash_commands/dsl_spec.rb
index 2763d950716..33b49a5ddf9 100644
--- a/spec/lib/gitlab/slash_commands/dsl_spec.rb
+++ b/spec/lib/gitlab/slash_commands/dsl_spec.rb
@@ -11,67 +11,99 @@ describe Gitlab::SlashCommands::Dsl do
       end
 
       params 'The first argument'
-      command :one_arg, :once, :first do |arg1|
-        arg1
+      explanation 'Static explanation'
+      command :explanation_with_aliases, :once, :first do |arg|
+        arg
       end
 
       desc do
         "A dynamic description for #{noteable.upcase}"
       end
       params 'The first argument', 'The second argument'
-      command :two_args do |arg1, arg2|
-        [arg1, arg2]
+      command :dynamic_description do |args|
+        args.split
       end
 
       command :cc
 
+      explanation do |arg|
+        "Action does something with #{arg}"
+      end
       condition do
         project == 'foo'
       end
       command :cond_action do |arg|
         arg
       end
+
+      parse_params do |raw_arg|
+        raw_arg.strip
+      end
+      command :with_params_parsing do |parsed|
+        parsed
+      end
     end
   end
 
   describe '.command_definitions' do
     it 'returns an array with commands definitions' do
-      no_args_def, one_arg_def, two_args_def, cc_def, cond_action_def = DummyClass.command_definitions
+      no_args_def, explanation_with_aliases_def, dynamic_description_def,
+      cc_def, cond_action_def, with_params_parsing_def =
+        DummyClass.command_definitions
 
       expect(no_args_def.name).to eq(:no_args)
       expect(no_args_def.aliases).to eq([:none])
       expect(no_args_def.description).to eq('A command with no args')
+      expect(no_args_def.explanation).to eq('')
       expect(no_args_def.params).to eq([])
       expect(no_args_def.condition_block).to be_nil
       expect(no_args_def.action_block).to be_a_kind_of(Proc)
+      expect(no_args_def.parse_params_block).to be_nil
 
-      expect(one_arg_def.name).to eq(:one_arg)
-      expect(one_arg_def.aliases).to eq([:once, :first])
-      expect(one_arg_def.description).to eq('')
-      expect(one_arg_def.params).to eq(['The first argument'])
-      expect(one_arg_def.condition_block).to be_nil
-      expect(one_arg_def.action_block).to be_a_kind_of(Proc)
+      expect(explanation_with_aliases_def.name).to eq(:explanation_with_aliases)
+      expect(explanation_with_aliases_def.aliases).to eq([:once, :first])
+      expect(explanation_with_aliases_def.description).to eq('')
+      expect(explanation_with_aliases_def.explanation).to eq('Static explanation')
+      expect(explanation_with_aliases_def.params).to eq(['The first argument'])
+      expect(explanation_with_aliases_def.condition_block).to be_nil
+      expect(explanation_with_aliases_def.action_block).to be_a_kind_of(Proc)
+      expect(explanation_with_aliases_def.parse_params_block).to be_nil
 
-      expect(two_args_def.name).to eq(:two_args)
-      expect(two_args_def.aliases).to eq([])
-      expect(two_args_def.to_h(noteable: "issue")[:description]).to eq('A dynamic description for ISSUE')
-      expect(two_args_def.params).to eq(['The first argument', 'The second argument'])
-      expect(two_args_def.condition_block).to be_nil
-      expect(two_args_def.action_block).to be_a_kind_of(Proc)
+      expect(dynamic_description_def.name).to eq(:dynamic_description)
+      expect(dynamic_description_def.aliases).to eq([])
+      expect(dynamic_description_def.to_h(noteable: 'issue')[:description]).to eq('A dynamic description for ISSUE')
+      expect(dynamic_description_def.explanation).to eq('')
+      expect(dynamic_description_def.params).to eq(['The first argument', 'The second argument'])
+      expect(dynamic_description_def.condition_block).to be_nil
+      expect(dynamic_description_def.action_block).to be_a_kind_of(Proc)
+      expect(dynamic_description_def.parse_params_block).to be_nil
 
       expect(cc_def.name).to eq(:cc)
       expect(cc_def.aliases).to eq([])
       expect(cc_def.description).to eq('')
+      expect(cc_def.explanation).to eq('')
       expect(cc_def.params).to eq([])
       expect(cc_def.condition_block).to be_nil
       expect(cc_def.action_block).to be_nil
+      expect(cc_def.parse_params_block).to be_nil
 
       expect(cond_action_def.name).to eq(:cond_action)
       expect(cond_action_def.aliases).to eq([])
       expect(cond_action_def.description).to eq('')
+      expect(cond_action_def.explanation).to be_a_kind_of(Proc)
       expect(cond_action_def.params).to eq([])
       expect(cond_action_def.condition_block).to be_a_kind_of(Proc)
       expect(cond_action_def.action_block).to be_a_kind_of(Proc)
+      expect(cond_action_def.parse_params_block).to be_nil
+
+      expect(with_params_parsing_def.name).to eq(:with_params_parsing)
+      expect(with_params_parsing_def.aliases).to eq([])
+      expect(with_params_parsing_def.description).to eq('')
+      expect(with_params_parsing_def.explanation).to eq('')
+      expect(with_params_parsing_def.params).to eq([])
+      expect(with_params_parsing_def.condition_block).to be_nil
+      expect(with_params_parsing_def.action_block).to be_a_kind_of(Proc)
+      expect(with_params_parsing_def.parse_params_block).to be_a_kind_of(Proc)
     end
   end
 end