1 files changed, 121 insertions, 0 deletions
diff --git a/spec/lib/gitlab/ci/config/yaml/tags/reference_spec.rb b/spec/lib/gitlab/ci/config/yaml/tags/reference_spec.rb
new file mode 100644
index 00000000000..c68dccd3455
--- /dev/null
+++ b/spec/lib/gitlab/ci/config/yaml/tags/reference_spec.rb
@@ -0,0 +1,121 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Ci::Config::Yaml::Tags::Reference do
+  let(:config) do
+    Gitlab::Ci::Config::Yaml.load!(yaml)
+  end
+
+  describe '.tag' do
+    it 'implements the tag method' do
+      expect(described_class.tag).to eq('!reference')
+    end
+  end
+
+  describe '#resolve' do
+    subject { Gitlab::Ci::Config::Yaml::Tags::Resolver.new(config).to_hash }
+
+    context 'with circular references' do
+      let(:yaml) do
+        <<~YML
+        a: !reference [b]
+        b: !reference [a]
+        YML
+      end
+
+      it 'raises CircularReferenceError' do
+        expect { subject }.to raise_error Gitlab::Ci::Config::Yaml::Tags::TagError, '!reference ["b"] is part of a circular chain'
+      end
+    end
+
+    context 'with nested circular references' do
+      let(:yaml) do
+        <<~YML
+        a: !reference [b, c]
+        b: { c: !reference [d, e, f] }
+        d: { e: { f: !reference [a] } }
+        YML
+      end
+
+      it 'raises CircularReferenceError' do
+        expect { subject }.to raise_error Gitlab::Ci::Config::Yaml::Tags::TagError, '!reference ["b", "c"] is part of a circular chain'
+      end
+    end
+
+    context 'with missing references' do
+      let(:yaml) { 'a: !reference [b]' }
+
+      it 'raises MissingReferenceError' do
+        expect { subject }.to raise_error Gitlab::Ci::Config::Yaml::Tags::TagError, '!reference ["b"] could not be found'
+      end
+    end
+
+    context 'with invalid references' do
+      using RSpec::Parameterized::TableSyntax
+
+      where(:yaml, :error_message) do
+        'a: !reference'          | '!reference [] is not valid'
+        'a: !reference str'      | '!reference "str" is not valid'
+        'a: !reference 1'        | '!reference "1" is not valid'
+        'a: !reference [1]'      | '!reference [1] is not valid'
+        'a: !reference { b: c }' | '!reference {"b"=>"c"} is not valid'
+      end
+
+      with_them do
+        it 'raises an error' do
+          expect { subject }.to raise_error Gitlab::Ci::Config::Yaml::Tags::TagError, error_message
+        end
+      end
+    end
+
+    context 'with arrays' do
+      let(:yaml) do
+        <<~YML
+        a: { b: [1, 2] }
+        c: { d: { e: [3, 4] } }
+        f: { g: [ !reference [a, b], 5, !reference [c, d, e]] }
+        YML
+      end
+
+      it { is_expected.to match(a_hash_including({ f: { g: [[1, 2], 5, [3, 4]] } })) }
+    end
+
+    context 'with hashes' do
+      context 'when referencing an entire hash' do
+        let(:yaml) do
+          <<~YML
+          a: { b: { c: 'c', d: 'd' } }
+          e: { f: !reference [a, b] }
+          YML
+        end
+
+        it { is_expected.to match(a_hash_including({ e: { f: { c: 'c', d: 'd' } } })) }
+      end
+
+      context 'when referencing only a hash value' do
+        let(:yaml) do
+          <<~YML
+          a: { b: { c: 'c', d: 'd' } }
+          e: {  f: { g: !reference [a, b, c], h: 'h' } }
+          i: !reference [e, f]
+          YML
+        end
+
+        it { is_expected.to match(a_hash_including({ i: { g: 'c', h: 'h' } })) }
+      end
+
+      context 'when referencing a value before its definition' do
+        let(:yaml) do
+          <<~YML
+          a: { b: !reference [c, d] }
+          g: { h: { i: 'i', j: 1 } }
+          c: { d: { e: !reference [g, h, j], f: 'f' } }
+          YML
+        end
+
+        it { is_expected.to match(a_hash_including({ a: { b: { e: 1, f: 'f' } } })) }
+      end
+    end
+  end
+end