1 files changed, 85 insertions, 0 deletions
diff --git a/spec/lib/gitlab/ci/pipeline/expression/statement_spec.rb b/spec/lib/gitlab/ci/pipeline/expression/statement_spec.rb
new file mode 100644
index 00000000000..472a58599d8
--- /dev/null
+++ b/spec/lib/gitlab/ci/pipeline/expression/statement_spec.rb
@@ -0,0 +1,85 @@
+require 'spec_helper'
+
+describe Gitlab::Ci::Pipeline::Expression::Statement do
+  let(:pipeline) { build(:ci_pipeline) }
+
+  subject do
+    described_class.new(text, pipeline)
+  end
+
+  before do
+    pipeline.variables.build([key: 'VARIABLE', value: 'my variable'])
+  end
+
+  describe '#parse_tree' do
+    context 'when expression is empty' do
+      let(:text) { '' }
+
+      it 'raises an error' do
+        expect { subject.parse_tree }
+          .to raise_error described_class::StatementError
+      end
+    end
+
+    context 'when expression grammar is incorrect' do
+      table = [
+        '$VAR "text"',      # missing operator
+        '== "123"',         # invalid right side
+        "'single quotes'",  # single quotes string
+        '$VAR ==',          # invalid right side
+        '12345',            # unknown syntax
+        ''                  # empty statement
+      ]
+
+      table.each do |syntax|
+        it "raises an error when syntax is `#{syntax}`" do
+          expect { described_class.new(syntax, pipeline).parse_tree }
+            .to raise_error described_class::StatementError
+        end
+      end
+    end
+
+    context 'when expression grammar is correct' do
+      context 'when using an operator' do
+        let(:text) { '$VAR == "value"' }
+
+        it 'returns a reverse descent parse tree' do
+          expect(subject.parse_tree)
+            .to be_a Gitlab::Ci::Pipeline::Expression::Lexeme::Equals
+        end
+      end
+
+      context 'when using a single token' do
+        let(:text) { '$VARIABLE' }
+
+        it 'returns a single token instance' do
+          expect(subject.parse_tree)
+            .to be_a Gitlab::Ci::Pipeline::Expression::Lexeme::Variable
+        end
+      end
+    end
+  end
+
+  describe '#evaluate' do
+    statements = [
+      ['$VARIABLE == "my variable"', true],
+      ["$VARIABLE == 'my variable'", true],
+      ['"my variable" == $VARIABLE', true],
+      ['$VARIABLE == null', false],
+      ['$VAR == null', true],
+      ['null == $VAR', true],
+      ['$VARIABLE', 'my variable'],
+      ['$VAR', nil]
+    ]
+
+    statements.each do |expression, value|
+      context "when using expression `#{expression}`" do
+        let(:text) { expression }
+
+        it "evaluates to `#{value.inspect}`" do
+          expect(subject.evaluate).to eq value
+        end
+      end
+    end
+  end
+end