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Test metric content instead of string representation #326

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Merged
chombium merged 1 commit into from
Jul 24, 2026
Merged

Test metric content instead of string representation #326

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41 changes: 35 additions & 6 deletions src/pkg/egress/stats/prom_registry_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,35 +20,64 @@ var _ = Describe("Prometheus Registry", func() {

It("registers the gauge when it's first gotten", func() {
gauge := toPromGauge(registry.Get("metric_name", "origin", "unit", nil))
Expect(gauge.Desc().String()).To(Equal(`Desc{fqName: "metric_name", help: "vm metric", constLabels: {unit="unit"}, variableLabels: {}}`))
expectGauge(gauge, "metric_name", map[string]string{"unit": "unit"})

var registered prometheus.Gauge
Eventually(registerer.gauges).Should(Receive(&registered))

Expect(registered.Desc().String()).To(Equal(`Desc{fqName: "metric_name", help: "vm metric", constLabels: {unit="unit"}, variableLabels: {}}`))
expectGauge(registered, "metric_name", map[string]string{"unit": "unit"})
})

It("doesn't reregister gauges", func() {
gauge := toPromGauge(registry.Get("metric_name", "origin", "unit", nil))
Expect(gauge.Desc().String()).To(Equal(`Desc{fqName: "metric_name", help: "vm metric", constLabels: {unit="unit"}, variableLabels: {}}`))
expectGauge(gauge, "metric_name", map[string]string{"unit": "unit"})

gauge = toPromGauge(registry.Get("metric_name", "origin", "unit", nil))
Expect(gauge.Desc().String()).To(Equal(`Desc{fqName: "metric_name", help: "vm metric", constLabels: {unit="unit"}, variableLabels: {}}`))
expectGauge(gauge, "metric_name", map[string]string{"unit": "unit"})

Expect(registerer.gauges).To(HaveLen(1))
})

It("gauges with different tags are different gauges", func() {
gauge := toPromGauge(registry.Get("metric_name", "origin", "unit", map[string]string{"foo": "bar2"}))
Expect(gauge.Desc().String()).To(Equal(`Desc{fqName: "metric_name", help: "vm metric", constLabels: {foo="bar2",unit="unit"}, variableLabels: {}}`))
expectGauge(gauge, "metric_name", map[string]string{"foo": "bar2", "unit": "unit"})

gauge = toPromGauge(registry.Get("metric_name", "origin", "unit", map[string]string{"foo": "bar"}))
Expect(gauge.Desc().String()).To(Equal(`Desc{fqName: "metric_name", help: "vm metric", constLabels: {foo="bar",unit="unit"}, variableLabels: {}}`))
expectGauge(gauge, "metric_name", map[string]string{"foo": "bar", "unit": "unit"})

Expect(registerer.gauges).To(HaveLen(2))
})
})

// gaugeDesc is a plain, comparable projection of a collected gauge's public
// contract (its exported name and const labels).
type gaugeDesc struct {
Name string
Labels map[string]string
}

// expectGauge collects the gauge through a real registry and compares its
// public contract against the expected name and const labels as a single object.
func expectGauge(g prometheus.Gauge, name string, constLabels map[string]string) {
GinkgoHelper()

reg := prometheus.NewRegistry()
Expect(reg.Register(g)).To(Succeed())

families, err := reg.Gather()
Expect(err).NotTo(HaveOccurred())
Expect(families).To(HaveLen(1))
Expect(families[0].GetMetric()).To(HaveLen(1))

labels := map[string]string{}
for _, p := range families[0].GetMetric()[0].GetLabel() {
labels[p.GetName()] = p.GetValue()
}

actual := gaugeDesc{Name: families[0].GetName(), Labels: labels}
Expect(actual).To(Equal(gaugeDesc{Name: name, Labels: constLabels}))
}

func toPromGauge(g stats.Gauge) prometheus.Gauge {
gauge, ok := g.(prometheus.Gauge)
Expect(ok).To(BeTrue())
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