Raise variables statement exception if pattern is invalid

lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb

@@ -11,8 +11,10 @@ module Gitlab
             end
 
             def evaluate(variables = {})
-              Gitlab::UntrustedRegexp.new(@value.to_s)
-              # TODO raise LexerError / ParserError in case of RegexpError
+              # TODO multiline support
+              @regexp = Gitlab::UntrustedRegexp.new(@value)
+            rescue RegexpError
+              raise Parser::ParserError, 'Invalid regular expression!'
             end
 
             def self.build(string)

lib/gitlab/ci/pipeline/expression/parser.rb

@@ -3,6 +3,8 @@ module Gitlab
     module Pipeline
       module Expression
         class Parser
+          ParserError = Class.new(Statement::StatementError)
+
           def initialize(tokens)
             @tokens = tokens.to_enum
             @nodes = []

spec/lib/gitlab/ci/pipeline/expression/lexeme/pattern_spec.rb

@@ -47,9 +47,16 @@ describe Gitlab::Ci::Pipeline::Expression::Lexeme::Pattern do
 
   describe '#evaluate' do
     it 'returns a regular expression' do
-      string = described_class.new('abc')
+      regexp = described_class.new('abc')
 
-      expect(string.evaluate).to eq Gitlab::UntrustedRegexp.new('abc')
+      expect(regexp.evaluate).to eq Gitlab::UntrustedRegexp.new('abc')
+    end
+
+    it 'raises error if evaluated regexp is not valid' do
+      regexp = described_class.new('invalid ( .*')
+
+      expect { regexp.evaluate }
+        .to raise_error(Gitlab::Ci::Pipeline::Expression::Parser::ParserError)
     end
   end
 end

spec/lib/gitlab/ci/pipeline/expression/parser_spec.rb

-require 'spec_helper'
+require 'fast_spec_helper'
 
 describe Gitlab::Ci::Pipeline::Expression::Parser do
   describe '#tree' do

spec/lib/gitlab/ci/pipeline/expression/token_spec.rb

-require 'spec_helper'
+require 'fast_spec_helper'
 
 describe Gitlab::Ci::Pipeline::Expression::Token do
   let(:value) { '$VARIABLE' }