Add testutils package

Signed-off-by: Frederic Branczyk <fbranczyk@gmail.com>
This commit is contained in:
Frederic Branczyk 2018-07-03 13:25:00 +02:00
parent d6a9817c4a
commit 5d3b089f0c
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2 changed files with 282 additions and 0 deletions

182
testutils/testutils.go Normal file
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/*
Copyright 2018 The Prometheus Authors All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package testutils
import (
"bytes"
"fmt"
"reflect"
"sort"
"strings"
"github.com/prometheus/client_golang/prometheus"
dto "github.com/prometheus/client_model/go"
"github.com/prometheus/common/expfmt"
)
// GatherAndCompare retrieves all metrics exposed by a collector and compares it
// to an expected output in the Prometheus text exposition format.
// metricNames allows only comparing the given metrics. All are compared if it's nil.
func GatherAndCompare(c prometheus.Collector, expected string, metricNames ...string) error {
expected = removeUnusedWhitespace(expected)
reg := prometheus.NewPedanticRegistry()
if err := reg.Register(c); err != nil {
return fmt.Errorf("registering collector failed: %s", err)
}
metrics, err := reg.Gather()
if err != nil {
return fmt.Errorf("gathering metrics failed: %s", err)
}
if metricNames != nil {
metrics = filterMetrics(metrics, metricNames)
}
var tp expfmt.TextParser
expectedMetrics, err := tp.TextToMetricFamilies(bytes.NewReader([]byte(expected)))
if err != nil {
return fmt.Errorf("parsing expected metrics failed: %s", err)
}
if !reflect.DeepEqual(metrics, normalizeMetricFamilies(expectedMetrics)) {
// Encode the gathered output to the readbale text format for comparison.
var buf1 bytes.Buffer
enc := expfmt.NewEncoder(&buf1, expfmt.FmtText)
for _, mf := range metrics {
if err := enc.Encode(mf); err != nil {
return fmt.Errorf("encoding result failed: %s", err)
}
}
// Encode normalized expected metrics again to generate them in the same ordering
// the registry does to spot differences more easily.
var buf2 bytes.Buffer
enc = expfmt.NewEncoder(&buf2, expfmt.FmtText)
for _, mf := range normalizeMetricFamilies(expectedMetrics) {
if err := enc.Encode(mf); err != nil {
return fmt.Errorf("encoding result failed: %s", err)
}
}
return fmt.Errorf(`
metric output does not match expectation; want:
%s
got:
%s
`, buf2.String(), buf1.String())
}
return nil
}
func filterMetrics(metrics []*dto.MetricFamily, names []string) []*dto.MetricFamily {
var filtered []*dto.MetricFamily
for _, m := range metrics {
drop := true
for _, name := range names {
if m.GetName() == name {
drop = false
break
}
}
if !drop {
filtered = append(filtered, m)
}
}
return filtered
}
func removeUnusedWhitespace(s string) string {
var (
trimmedLine string
trimmedLines []string
lines = strings.Split(s, "\n")
)
for _, l := range lines {
trimmedLine = strings.TrimSpace(l)
if len(trimmedLine) > 0 {
trimmedLines = append(trimmedLines, trimmedLine)
}
}
// The Prometheus metrics representation parser expects an empty line at the
// end otherwise fails with an unexpected EOF error.
return strings.Join(trimmedLines, "\n") + "\n"
}
// The below sorting code is copied form the Prometheus client library modulo the added
// label pair sorting.
// https://github.com/prometheus/client_golang/blob/ea6e1db4cb8127eeb0b6954f7320363e5451820f/prometheus/registry.go#L642-L684
// metricSorter is a sortable slice of *dto.Metric.
type metricSorter []*dto.Metric
func (s metricSorter) Len() int {
return len(s)
}
func (s metricSorter) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
func (s metricSorter) Less(i, j int) bool {
sort.Sort(prometheus.LabelPairSorter(s[i].Label))
sort.Sort(prometheus.LabelPairSorter(s[j].Label))
if len(s[i].Label) != len(s[j].Label) {
return len(s[i].Label) < len(s[j].Label)
}
for n, lp := range s[i].Label {
vi := lp.GetValue()
vj := s[j].Label[n].GetValue()
if vi != vj {
return vi < vj
}
}
if s[i].TimestampMs == nil {
return false
}
if s[j].TimestampMs == nil {
return true
}
return s[i].GetTimestampMs() < s[j].GetTimestampMs()
}
// normalizeMetricFamilies returns a MetricFamily slice with empty
// MetricFamilies pruned and the remaining MetricFamilies sorted by name within
// the slice, with the contained Metrics sorted within each MetricFamily.
func normalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily) []*dto.MetricFamily {
for _, mf := range metricFamiliesByName {
sort.Sort(metricSorter(mf.Metric))
}
names := make([]string, 0, len(metricFamiliesByName))
for name, mf := range metricFamiliesByName {
if len(mf.Metric) > 0 {
names = append(names, name)
}
}
sort.Strings(names)
result := make([]*dto.MetricFamily, 0, len(names))
for _, name := range names {
result = append(result, metricFamiliesByName[name])
}
return result
}

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testutils/testutils_test.go Normal file
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package testutils
import (
"testing"
"github.com/prometheus/client_golang/prometheus"
)
func TestGatherAndCompare(t *testing.T) {
const metadata = `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
`
c := prometheus.NewCounter(prometheus.CounterOpts{
Name: "some_total",
Help: "A value that represents a counter.",
ConstLabels: prometheus.Labels{
"label1": "value1",
},
})
c.Inc()
expected := `
some_total{label1="value1"} 1
`
if err := GatherAndCompare(c, metadata+expected, "some_total"); err != nil {
t.Errorf("unexpected collecting result:\n%s", err)
}
}
func TestNoMetricFilter(t *testing.T) {
const metadata = `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
`
c := prometheus.NewCounter(prometheus.CounterOpts{
Name: "some_total",
Help: "A value that represents a counter.",
ConstLabels: prometheus.Labels{
"label1": "value1",
},
})
c.Inc()
expected := `
some_total{label1="value1"} 1
`
if err := GatherAndCompare(c, metadata+expected); err != nil {
t.Errorf("unexpected collecting result:\n%s", err)
}
}
func TestMetricNotFound(t *testing.T) {
const metadata = `
# HELP some_other_metric A value that represents a counter.
# TYPE some_other_metric counter
`
c := prometheus.NewCounter(prometheus.CounterOpts{
Name: "some_total",
Help: "A value that represents a counter.",
ConstLabels: prometheus.Labels{
"label1": "value1",
},
})
c.Inc()
expected := `
some_other_metric{label1="value1"} 1
`
expectedError := `
metric output does not match expectation; want:
# HELP some_other_metric A value that represents a counter.
# TYPE some_other_metric counter
some_other_metric{label1="value1"} 1
got:
# HELP some_total A value that represents a counter.
# TYPE some_total counter
some_total{label1="value1"} 1
`
err := GatherAndCompare(c, metadata+expected)
if err == nil {
t.Error("Expected error, got no error.")
}
if err.Error() != expectedError {
t.Errorf("Expected\n%#+v\nGot:\n%#+v\n", expectedError, err.Error())
}
}