Add testutils package
Signed-off-by: Frederic Branczyk <fbranczyk@gmail.com>
This commit is contained in:
Frederic Branczyk
parent
d6a9817c4a
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/*
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Copyright 2018 The Prometheus Authors All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package testutils
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import (
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"bytes"
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"fmt"
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"reflect"
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"sort"
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"strings"
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"github.com/prometheus/client_golang/prometheus"
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dto "github.com/prometheus/client_model/go"
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"github.com/prometheus/common/expfmt"
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)
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// GatherAndCompare retrieves all metrics exposed by a collector and compares it
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// to an expected output in the Prometheus text exposition format.
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// metricNames allows only comparing the given metrics. All are compared if it's nil.
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func GatherAndCompare(c prometheus.Collector, expected string, metricNames ...string) error {
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expected = removeUnusedWhitespace(expected)
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reg := prometheus.NewPedanticRegistry()
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if err := reg.Register(c); err != nil {
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return fmt.Errorf("registering collector failed: %s", err)
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}
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metrics, err := reg.Gather()
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if err != nil {
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return fmt.Errorf("gathering metrics failed: %s", err)
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}
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if metricNames != nil {
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metrics = filterMetrics(metrics, metricNames)
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}
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var tp expfmt.TextParser
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expectedMetrics, err := tp.TextToMetricFamilies(bytes.NewReader([]byte(expected)))
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if err != nil {
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return fmt.Errorf("parsing expected metrics failed: %s", err)
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}
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if !reflect.DeepEqual(metrics, normalizeMetricFamilies(expectedMetrics)) {
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// Encode the gathered output to the readbale text format for comparison.
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var buf1 bytes.Buffer
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enc := expfmt.NewEncoder(&buf1, expfmt.FmtText)
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for _, mf := range metrics {
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if err := enc.Encode(mf); err != nil {
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return fmt.Errorf("encoding result failed: %s", err)
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}
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}
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// Encode normalized expected metrics again to generate them in the same ordering
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// the registry does to spot differences more easily.
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var buf2 bytes.Buffer
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enc = expfmt.NewEncoder(&buf2, expfmt.FmtText)
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for _, mf := range normalizeMetricFamilies(expectedMetrics) {
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if err := enc.Encode(mf); err != nil {
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return fmt.Errorf("encoding result failed: %s", err)
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}
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}
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return fmt.Errorf(`
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metric output does not match expectation; want:
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%s
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got:
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%s
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`, buf2.String(), buf1.String())
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}
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return nil
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}
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func filterMetrics(metrics []*dto.MetricFamily, names []string) []*dto.MetricFamily {
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var filtered []*dto.MetricFamily
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for _, m := range metrics {
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drop := true
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for _, name := range names {
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if m.GetName() == name {
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drop = false
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break
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}
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}
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if !drop {
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filtered = append(filtered, m)
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}
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}
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return filtered
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}
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func removeUnusedWhitespace(s string) string {
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var (
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trimmedLine string
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trimmedLines []string
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lines = strings.Split(s, "\n")
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)
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for _, l := range lines {
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trimmedLine = strings.TrimSpace(l)
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if len(trimmedLine) > 0 {
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trimmedLines = append(trimmedLines, trimmedLine)
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}
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}
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// The Prometheus metrics representation parser expects an empty line at the
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// end otherwise fails with an unexpected EOF error.
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return strings.Join(trimmedLines, "\n") + "\n"
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}
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// The below sorting code is copied form the Prometheus client library modulo the added
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// label pair sorting.
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// https://github.com/prometheus/client_golang/blob/ea6e1db4cb8127eeb0b6954f7320363e5451820f/prometheus/registry.go#L642-L684
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// metricSorter is a sortable slice of *dto.Metric.
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type metricSorter []*dto.Metric
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func (s metricSorter) Len() int {
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return len(s)
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}
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func (s metricSorter) Swap(i, j int) {
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s[i], s[j] = s[j], s[i]
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}
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func (s metricSorter) Less(i, j int) bool {
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sort.Sort(prometheus.LabelPairSorter(s[i].Label))
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sort.Sort(prometheus.LabelPairSorter(s[j].Label))
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if len(s[i].Label) != len(s[j].Label) {
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return len(s[i].Label) < len(s[j].Label)
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}
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for n, lp := range s[i].Label {
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vi := lp.GetValue()
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vj := s[j].Label[n].GetValue()
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if vi != vj {
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return vi < vj
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}
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}
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if s[i].TimestampMs == nil {
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return false
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}
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if s[j].TimestampMs == nil {
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return true
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}
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return s[i].GetTimestampMs() < s[j].GetTimestampMs()
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}
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// normalizeMetricFamilies returns a MetricFamily slice with empty
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// MetricFamilies pruned and the remaining MetricFamilies sorted by name within
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// the slice, with the contained Metrics sorted within each MetricFamily.
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func normalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily) []*dto.MetricFamily {
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for _, mf := range metricFamiliesByName {
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sort.Sort(metricSorter(mf.Metric))
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}
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names := make([]string, 0, len(metricFamiliesByName))
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for name, mf := range metricFamiliesByName {
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if len(mf.Metric) > 0 {
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names = append(names, name)
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}
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}
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sort.Strings(names)
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result := make([]*dto.MetricFamily, 0, len(names))
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for _, name := range names {
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result = append(result, metricFamiliesByName[name])
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}
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return result
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}
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@ -0,0 +1,100 @@
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package testutils
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import (
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"testing"
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"github.com/prometheus/client_golang/prometheus"
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)
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func TestGatherAndCompare(t *testing.T) {
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const metadata = `
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# HELP some_total A value that represents a counter.
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# TYPE some_total counter
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`
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c := prometheus.NewCounter(prometheus.CounterOpts{
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Name: "some_total",
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Help: "A value that represents a counter.",
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ConstLabels: prometheus.Labels{
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"label1": "value1",
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},
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})
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c.Inc()
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expected := `
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some_total{label1="value1"} 1
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`
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if err := GatherAndCompare(c, metadata+expected, "some_total"); err != nil {
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t.Errorf("unexpected collecting result:\n%s", err)
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}
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}
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func TestNoMetricFilter(t *testing.T) {
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const metadata = `
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# HELP some_total A value that represents a counter.
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# TYPE some_total counter
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`
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c := prometheus.NewCounter(prometheus.CounterOpts{
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Name: "some_total",
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Help: "A value that represents a counter.",
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ConstLabels: prometheus.Labels{
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"label1": "value1",
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},
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})
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c.Inc()
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expected := `
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some_total{label1="value1"} 1
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`
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if err := GatherAndCompare(c, metadata+expected); err != nil {
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t.Errorf("unexpected collecting result:\n%s", err)
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}
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}
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func TestMetricNotFound(t *testing.T) {
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const metadata = `
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# HELP some_other_metric A value that represents a counter.
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# TYPE some_other_metric counter
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`
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c := prometheus.NewCounter(prometheus.CounterOpts{
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Name: "some_total",
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Help: "A value that represents a counter.",
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ConstLabels: prometheus.Labels{
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"label1": "value1",
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},
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})
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c.Inc()
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expected := `
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some_other_metric{label1="value1"} 1
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`
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expectedError := `
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metric output does not match expectation; want:
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# HELP some_other_metric A value that represents a counter.
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# TYPE some_other_metric counter
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some_other_metric{label1="value1"} 1
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got:
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# HELP some_total A value that represents a counter.
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# TYPE some_total counter
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some_total{label1="value1"} 1
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`
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err := GatherAndCompare(c, metadata+expected)
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if err == nil {
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t.Error("Expected error, got no error.")
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}
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if err.Error() != expectedError {
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t.Errorf("Expected\n%#+v\nGot:\n%#+v\n", expectedError, err.Error())
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}
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}
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