Add support for single quoted string in pipeline expressions

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

@@ -4,7 +4,7 @@ module Gitlab
       module Expression
         module Lexeme
           class String < Lexeme::Value
-            PATTERN = /"(?<string>.+?)"/.freeze
+            PATTERN = /("(?<string>.+?)")|('(?<string>.+?)')/.freeze
 
             def initialize(value)
               @value = value

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

@@ -14,6 +14,68 @@ describe Gitlab::Ci::Pipeline::Expression::Lexeme::String do
     end
   end
 
+  describe '.scan' do
+    context 'when using double quotes' do
+      it 'correctly identifies string token' do
+        scanner = StringScanner.new('"some string"')
+
+        token = described_class.scan(scanner)
+
+        expect(token).not_to be_nil
+        expect(token.build.evaluate).to eq 'some string'
+      end
+    end
+
+    context 'when using single quotes' do
+      it 'correctly identifies string token' do
+        scanner = StringScanner.new("'some string 2'")
+
+        token = described_class.scan(scanner)
+
+        expect(token).not_to be_nil
+        expect(token.build.evaluate).to eq 'some string 2'
+      end
+    end
+
+    context 'when there are mixed quotes in the string' do
+      it 'is a greedy scanner for double quotes' do
+        scanner = StringScanner.new('"some string" "and another one"')
+
+        token = described_class.scan(scanner)
+
+        expect(token).not_to be_nil
+        expect(token.build.evaluate).to eq 'some string'
+      end
+
+      it 'is a greedy scanner for single quotes' do
+        scanner = StringScanner.new("'some string' 'and another one'")
+
+        token = described_class.scan(scanner)
+
+        expect(token).not_to be_nil
+        expect(token.build.evaluate).to eq 'some string'
+      end
+
+      it 'allows to use single quotes inside double quotes' do
+        scanner = StringScanner.new(%("some ' string"))
+
+        token = described_class.scan(scanner)
+
+        expect(token).not_to be_nil
+        expect(token.build.evaluate).to eq "some ' string"
+      end
+
+      it 'allow to use double quotes inside single quotes' do
+        scanner = StringScanner.new(%('some " string'))
+
+        token = described_class.scan(scanner)
+
+        expect(token).not_to be_nil
+        expect(token.build.evaluate).to eq 'some " string'
+      end
+    end
+  end
+
   describe '#evaluate' do
     it 'returns string value it is is present' do
       string = described_class.new('my string')

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

@@ -64,6 +64,7 @@ describe Gitlab::Ci::Pipeline::Expression::Statement do
   describe '#evaluate' do
     statements = [
       ['$VARIABLE == "my variable"', true],
+      ["$VARIABLE == 'my variable'", true],
       ['"my variable" == $VARIABLE', true],
       ['$VARIABLE == null', false],
       ['$VAR == null', true],