Add class method to encapsulate exception

app/controllers/ci/lints_controller.rb

@@ -11,15 +11,15 @@ module Ci
       if @content.blank?
         @status = false
         @error = "Please provide content of .gitlab-ci.yml"
+      elsif Ci::GitlabCiYamlProcessor.validate(@content) != "valid"
+        @status = false
+        @error = Ci::GitlabCiYamlProcessor.validate(@content)
       else
         @config_processor = Ci::GitlabCiYamlProcessor.new(@content)
         @stages = @config_processor.stages
         @builds = @config_processor.builds
         @status = true
       end
-    rescue Ci::GitlabCiYamlProcessor::ValidationError, Psych::SyntaxError => e
-      @error = e.message
-      @status = false
     rescue
       @error = 'Undefined error'
       @status = false

lib/api/lint.rb

@@ -7,31 +7,29 @@ module API
       desc 'Validation of .gitlab-ci.yml content'
       post do
-        status 200
-
-        begin
-          response = {
-            status: '',
-            errors: [],
-            jobs: []
-          }
-
-          config_processor = Ci::GitlabCiYamlProcessor.new(params[:content])
-
-          config_processor.builds.each do |build|
-            response[:jobs].push("#{build[:name]}")
-            response[:status] = 'valid'
-          end
-
-          response
-        rescue Ci::GitlabCiYamlProcessor::ValidationError, Psych::SyntaxError => e
+        response = {
+          status: '',
+          errors: [],
+          jobs: []
+        }
+        if Ci::GitlabCiYamlProcessor.validate(@content) != "valid"
           status 200
           response[:errors].push(e.message)
           response[:status] = 'invalid'
           response
         end
+
+        config_processor = Ci::GitlabCiYamlProcessor.new(params[:content])
+
+        config_processor.builds.each do |build|
+          response[:jobs].push("#{build[:name]}")
+          response[:status] = 'valid'
+        end
+
+        status 200
+        response
       end
     end
   end

lib/ci/gitlab_ci_yaml_processor.rb

@@ -78,6 +78,15 @@ module Ci
       }
     end
+    def self.validate(content)
+      begin
+        Ci::GitlabCiYamlProcessor.new(content)
+        "valid"
+      rescue ValidationError, Psych::SyntaxError => e
+        e.message
+      end
+    end
+
     private
     def initial_parsing

spec/lib/ci/gitlab_ci_yaml_processor_spec.rb

@@ -1250,5 +1250,24 @@ EOT
         end
       end
     end
+
+    describe "#validate(config)" do
+      describe "Error handling" do
+        it "returns error to parse YAML" do
+          config = YAML.dump("invalid: yaml: test")
+          expect(GitlabCiYamlProcessor.validate(config)).to eq "Invalid configuration format"
+        end
+
+        it "returns errors if tags parameter is invalid" do
+          config = YAML.dump({ rspec: { script: "test", tags: "mysql" } })
+          expect(GitlabCiYamlProcessor.validate(config)).to eq "jobs:rspec tags should be an array of strings"
+        end
+
+        it "does not return errors" do
+          config = File.read(Rails.root.join('spec/support/gitlab_stubs/gitlab_ci.yml'))
+          expect(GitlabCiYamlProcessor.validate(config)).to eq "valid"
+        end
+      end
+    end
   end
 end