test: clarify comments in error-propagation test and benchmark per code review

Co-authored-by: nitrocode <7775707+nitrocode@users.noreply.github.com>
Agent-Logs-Url: https://github.com/cloudposse/atmos/sessions/93ee2135-1e5b-487d-94f5-e3af9cc1f548

Author: Copilot

internal/exec/terraform_execute_helpers_workspace_test.go

@@ -181,8 +181,10 @@ func TestExecuteMainTerraformCommand_BareWorkspace_ReturnsNil(t *testing.T) {
 // error is propagated to the caller rather than being swallowed.
 //
 // Cross-platform approach: uses the test binary itself (os.Executable) with
-// _ATMOS_TEST_EXIT_ONE=1 to produce a portable exit-1 without depending on Unix-only
-// binaries like "false".  TestMain in testmain_test.go intercepts this env var.
+// _ATMOS_TEST_EXIT_ONE=1 as the "terraform" command.  TestMain in testmain_test.go
+// intercepts this env var and calls os.Exit(1) immediately — before the test runner
+// starts.  The -test.run argument is irrelevant since TestMain exits before any test
+// selection happens, but it is included for documentation clarity.
 //
 // This test also acts as a contract test that ExecuteShellCommand correctly wraps
 // subprocess exit codes in errUtils.ExitCodeError: errors.As must succeed.

pkg/merge/merge_native_test.go

@@ -908,9 +908,10 @@ func BenchmarkMergeNative_TenInputs(b *testing.B) {
 
 // BenchmarkMerge_ProductionScale simulates a realistic large-stack merge:
 // 10 inheritance layers, 25 top-level sections, nested maps, mixed lists, and
-// nested list-of-map-of-list (node_groups with per-group subnet lists) — the
-// last pattern exercises the full sliceDeepCopy and appendSlice code paths
-// with deeply nested structures representative of real Atmos stacks.
+// the nested list-of-map-of-list pattern (`node_groups` with per-group subnet lists).
+// The `node_groups` structure exercises the full sliceDeepCopy and appendSlice code
+// paths with deeply nested structures representative of real Atmos stacks (e.g.
+// EKS node groups with per-group subnet, label, and tag lists).
 // This supplements BenchmarkMergeNative_TenInputs which uses only 3 top-level keys.
 // Production Atmos stacks typically have 10–30 sections and 5–15 inheritance levels.
 //