some tests

main_test.go

@@ -0,0 +1,51 @@
+package nebula
+
+import (
+	"testing"
+
+	"github.com/slackhq/nebula/config"
+	"github.com/slackhq/nebula/test"
+	"github.com/slackhq/nebula/util"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParseCpuAffinity(t *testing.T) {
+	l := test.NewLogger()
+
+	// newConfig returns a config.C with tun.cpu_affinity set to v. A nil v
+	// leaves the key unset.
+	newConfig := func(v any) *config.C {
+		c := config.NewC(l)
+		if v != nil {
+			c.Settings["tun"] = map[string]any{"cpu_affinity": v}
+		}
+		return c
+	}
+
+	// unset -> nil (listenIn falls back to spreading across the allowed set)
+	assert.Nil(t, parseCpuAffinity(newConfig(nil), l, 1))
+
+	// Pick a CPU we're actually allowed to run on so a valid list survives
+	// validation regardless of the host's affinity mask.
+	allowed, _ := util.AllowedCPUs()
+	validCPU := 0
+	if len(allowed) > 0 {
+		validCPU = allowed[0]
+	}
+
+	// valid list -> parsed through unchanged
+	assert.Equal(t, []int{validCPU, validCPU}, parseCpuAffinity(newConfig([]any{validCPU, validCPU}), l, 2))
+
+	// a negative entry is out of range on every platform -> disables the override
+	assert.Nil(t, parseCpuAffinity(newConfig([]any{validCPU, -1}), l, 2))
+
+	// a non-integer entry -> disables the override
+	assert.Nil(t, parseCpuAffinity(newConfig([]any{validCPU, "not-a-cpu"}), l, 2))
+
+	// a CPU id outside the allowed set -> disables the override. Only assertable
+	// where we can enumerate the allowed set (e.g. linux); 1<<20 is far beyond
+	// any representable CPU id so it can never be in the mask.
+	if len(allowed) > 0 {
+		assert.Nil(t, parseCpuAffinity(newConfig([]any{1 << 20}), l, 1))
+	}
+}