1 files changed, 95 insertions, 0 deletions
diff --git a/spec/lib/error_tracking/stacktrace_builder_spec.rb b/spec/lib/error_tracking/stacktrace_builder_spec.rb
new file mode 100644
index 00000000000..46d0bde8122
--- /dev/null
+++ b/spec/lib/error_tracking/stacktrace_builder_spec.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'support/helpers/fast_rails_root'
+require 'oj'
+
+RSpec.describe ErrorTracking::StacktraceBuilder do
+  include FastRailsRoot
+
+  describe '#stacktrace' do
+    let(:original_payload) { Gitlab::Json.parse(File.read(rails_root_join('spec/fixtures', payload_file))) }
+    let(:payload) { original_payload }
+    let(:payload_file) { 'error_tracking/parsed_event.json' }
+
+    subject(:stacktrace) { described_class.new(payload).stacktrace }
+
+    context 'with full error context' do
+      it 'generates a correct stacktrace in expected format' do
+        expected_context = [
+          [132, "          end\n"],
+          [133, "\n"],
+          [134, "          begin\n"],
+          [135, "            block.call(work, *extra)\n"],
+          [136, "          rescue Exception => e\n"],
+          [137, "            STDERR.puts \"Error reached top of thread-pool: #\{e.message\} (#\{e.class\})\"\n"],
+          [138, "          end\n"]
+        ]
+
+        expected_entry = {
+          'lineNo' => 135,
+          'context' => expected_context,
+          'filename' => 'puma/thread_pool.rb',
+          'function' => 'block in spawn_thread',
+          'colNo' => 0
+        }
+
+        expect(stacktrace).to be_kind_of(Array)
+        expect(stacktrace.first).to eq(expected_entry)
+      end
+    end
+
+    context 'when error context is missing' do
+      let(:payload_file) { 'error_tracking/browser_event.json' }
+
+      it 'generates a stacktrace without context' do
+        expected_entry = {
+          'lineNo' => 6395,
+          'context' => [],
+          'filename' => 'webpack-internal:///./node_modules/vue/dist/vue.runtime.esm.js',
+          'function' => 'hydrate',
+          'colNo' => 0
+        }
+
+        expect(stacktrace).to be_kind_of(Array)
+        expect(stacktrace.first).to eq(expected_entry)
+      end
+    end
+
+    context 'with empty payload' do
+      let(:payload) { {} }
+
+      it { is_expected.to eq([]) }
+    end
+
+    context 'without exception field' do
+      let(:payload) { original_payload.except('exception') }
+
+      it { is_expected.to eq([]) }
+    end
+
+    context 'without exception.values field' do
+      before do
+        original_payload['exception'].delete('values')
+      end
+
+      it { is_expected.to eq([]) }
+    end
+
+    context 'without any exception.values[].stacktrace fields' do
+      before do
+        original_payload.dig('exception', 'values').each { |value| value['stacktrace'] = '' }
+      end
+
+      it { is_expected.to eq([]) }
+    end
+
+    context 'without any exception.values[].stacktrace.frame fields' do
+      before do
+        original_payload.dig('exception', 'values').each { |value| value['stacktrace'].delete('frames') }
+      end
+
+      it { is_expected.to eq([]) }
+    end
+  end
+end