Validate job-level variables in YAML config file

lib/ci/gitlab_ci_yaml_processor.rb

@@ -153,6 +153,7 @@ module Ci
       validate_job_types!(name, job)
 
       validate_job_stage!(name, job) if job[:stage]
+      validate_job_variables!(name, job) if job[:variables]
       validate_job_cache!(name, job) if job[:cache]
       validate_job_artifacts!(name, job) if job[:artifacts]
       validate_job_dependencies!(name, job) if job[:dependencies]
@@ -214,6 +215,13 @@ module Ci
       end
     end
 
+    def validate_job_variables!(name, job)
+      if job[:variables] && !validate_variables(job[:variables])
+        raise ValidationError,
+          "#{name} job: variables should be a map of key-valued strings"
+      end
+    end
+
     def validate_job_cache!(name, job)
       if job[:cache][:key] && !validate_string(job[:cache][:key])
         raise ValidationError, "#{name} job: cache:key parameter should be a string"

spec/lib/ci/gitlab_ci_yaml_processor_spec.rb

@@ -366,6 +366,7 @@ module Ci
       end
 
       context 'when job variables are defined' do
+        context 'when syntax is correct' do
           it 'returns job variables' do
             variables =  {
               KEY1: 'value1',
@@ -385,6 +386,24 @@ module Ci
           end
         end
 
+        context 'when syntax is incorrect' do
+          it 'raises error' do
+            variables = [:KEY1, 'value1', :KEY2, 'value2']
+
+            config =  YAML.dump(
+              { before_script: ['pwd'],
+                rspec: {
+                  variables: variables,
+                  script: 'rspec' }
+              })
+
+            expect { GitlabCiYamlProcessor.new(config, path) }
+              .to raise_error(GitlabCiYamlProcessor::ValidationError,
+                               /job: variables should be a map/)
+          end
+        end
+      end
+
       context 'when job variables are not defined' do
         it 'returns empty array' do
           config = YAML.dump({