1 files changed, 54 insertions, 0 deletions
diff --git a/version/cmdname_test.go b/version/cmdname_test.go
new file mode 100644
index 000000000..94f4e984d
--- /dev/null
+++ b/version/cmdname_test.go
@@ -0,0 +1,54 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !ios
+
+package version_test
+
+import (
+	"testing"
+
+	"tailscale.com/tstest"
+	"tailscale.com/version"
+)
+
+// TestCmdNameFromBuildInfo asserts that CmdName recovers its result from the
+// running binary's embedded Go module info (via runtime/debug.ReadBuildInfo)
+// rather than returning the os.Executable-based fallback. When this test is
+// run under "go test tailscale.com/version", the test binary's embedded
+// build-info Path is "tailscale.com/version.test", so CmdName should return
+// "version.test". The on-disk basename of the test binary (something like
+// "version.test" in a go-build temp dir with random suffixes) is also
+// typically "version.test", but the import-path derivation is what we care
+// about: it is the only route by which a binary installed under an arbitrary
+// name (e.g. "tailscaled-linux-amd64") still reports itself as "tailscaled".
+func TestCmdNameFromBuildInfo(t *testing.T) {
+	if got, want := version.CmdName(), "version.test"; got != want {
+		t.Errorf("CmdName() = %q, want %q", got, want)
+	}
+}
+
+// BenchmarkCmdName measures the cost of the public, memoized CmdName.
+// After a one-time warmup (which itself does no filesystem I/O, just an
+// in-memory string lookup), this should be a trivial atomic load with zero
+// allocations.
+func BenchmarkCmdName(b *testing.B) {
+	_ = version.CmdName() // prime
+	b.ReportAllocs()
+	b.ResetTimer()
+	for range b.N {
+		_ = version.CmdName()
+	}
+}
+
+// TestCmdNameNoAllocs asserts that the public CmdName, once primed, performs
+// no allocations. This guards against regressions that reintroduce per-call
+// binary parsing.
+func TestCmdNameNoAllocs(t *testing.T) {
+	_ = version.CmdName() // prime
+	if err := tstest.MinAllocsPerRun(t, 0, func() {
+		_ = version.CmdName()
+	}); err != nil {
+		t.Error(err)
+	}
+}