1 files changed, 26 insertions, 0 deletions
diff --git a/spec/lib/gitlab/ci/pipeline/expression/parser_spec.rb b/spec/lib/gitlab/ci/pipeline/expression/parser_spec.rb
new file mode 100644
index 00000000000..e8e6f585310
--- /dev/null
+++ b/spec/lib/gitlab/ci/pipeline/expression/parser_spec.rb
@@ -0,0 +1,26 @@
+require 'spec_helper'
+
+describe Gitlab::Ci::Pipeline::Expression::Parser do
+  describe '#tree' do
+    context 'when using operators' do
+      it 'returns a reverse descent parse tree' do
+        expect(described_class.seed('$VAR1 == "123" == $VAR2').tree)
+          .to be_a Gitlab::Ci::Pipeline::Expression::Lexeme::Equals
+      end
+    end
+
+    context 'when using a single token' do
+      it 'returns a single token instance' do
+        expect(described_class.seed('$VAR').tree)
+          .to be_a Gitlab::Ci::Pipeline::Expression::Lexeme::Variable
+      end
+    end
+
+    context 'when expression is empty' do
+      it 'returns a null token' do
+        expect(described_class.seed('').tree)
+          .to be_a Gitlab::Ci::Pipeline::Expression::Lexeme::Null
+      end
+    end
+  end
+end