1 files changed, 153 insertions, 0 deletions
diff --git a/spec/lib/gitlab/ci/config/yaml/loader_spec.rb b/spec/lib/gitlab/ci/config/yaml/loader_spec.rb
new file mode 100644
index 00000000000..1e417bcd8af
--- /dev/null
+++ b/spec/lib/gitlab/ci/config/yaml/loader_spec.rb
@@ -0,0 +1,153 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Ci::Config::Yaml::Loader, feature_category: :pipeline_composition do
+  describe '#to_result' do
+    let_it_be(:project) { create(:project) }
+
+    subject(:result) { described_class.new(yaml, project: project).to_result }
+
+    context 'when syntax is invalid' do
+      let(:yaml) { 'some: invalid: syntax' }
+
+      it 'returns an invalid result object' do
+        expect(result).not_to be_valid
+        expect(result.error).to be_a ::Gitlab::Config::Loader::FormatError
+      end
+    end
+
+    context 'when the first document is a header' do
+      context 'with explicit document start marker' do
+        let(:yaml) do
+          <<~YAML
+            ---
+            spec:
+            ---
+            b: 2
+          YAML
+        end
+
+        it 'considers the first document as header and the second as content' do
+          expect(result).to be_valid
+          expect(result.error).to be_nil
+          expect(result.header).to eq({ spec: nil })
+          expect(result.content).to eq({ b: 2 })
+        end
+      end
+    end
+
+    context 'when first document is empty' do
+      let(:yaml) do
+        <<~YAML
+          ---
+          ---
+          b: 2
+        YAML
+      end
+
+      it 'considers the first document as header and the second as content' do
+        expect(result).not_to have_header
+      end
+    end
+
+    context 'when first document is an empty hash' do
+      let(:yaml) do
+        <<~YAML
+          {}
+          ---
+          b: 2
+        YAML
+      end
+
+      it 'returns second document as a content' do
+        expect(result).not_to have_header
+        expect(result.content).to eq({ b: 2 })
+      end
+    end
+
+    context 'when first an array' do
+      let(:yaml) do
+        <<~YAML
+          ---
+           - a
+           - b
+          ---
+          b: 2
+        YAML
+      end
+
+      it 'considers the first document as header and the second as content' do
+        expect(result).not_to have_header
+      end
+    end
+
+    context 'when the first document is not a header' do
+      let(:yaml) do
+        <<~YAML
+          a: 1
+          ---
+          b: 2
+        YAML
+      end
+
+      it 'considers the first document as content for backwards compatibility' do
+        expect(result).to be_valid
+        expect(result.error).to be_nil
+        expect(result).not_to have_header
+        expect(result.content).to eq({ a: 1 })
+      end
+
+      context 'with explicit document start marker' do
+        let(:yaml) do
+          <<~YAML
+            ---
+            a: 1
+            ---
+            b: 2
+          YAML
+        end
+
+        it 'considers the first document as content for backwards compatibility' do
+          expect(result).to be_valid
+          expect(result.error).to be_nil
+          expect(result).not_to have_header
+          expect(result.content).to eq({ a: 1 })
+        end
+      end
+    end
+
+    context 'when the first document is not a header and second document is empty' do
+      let(:yaml) do
+        <<~YAML
+          a: 1
+          ---
+        YAML
+      end
+
+      it 'considers the first document as content' do
+        expect(result).to be_valid
+        expect(result.error).to be_nil
+        expect(result).not_to have_header
+        expect(result.content).to eq({ a: 1 })
+      end
+
+      context 'with explicit document start marker' do
+        let(:yaml) do
+          <<~YAML
+            ---
+            a: 1
+            ---
+          YAML
+        end
+
+        it 'considers the first document as content' do
+          expect(result).to be_valid
+          expect(result.error).to be_nil
+          expect(result).not_to have_header
+          expect(result.content).to eq({ a: 1 })
+        end
+      end
+    end
+  end
+end