Merge branch 'testutils' of git://github.com/brancz/client_golang into beorn7/testing

testutils/testutils.go

@@ -0,0 +1,182 @@
+/*
+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
+}

testutils/testutils_test.go

@@ -0,0 +1,100 @@
+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())
+	}
+}