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Merge pull request #1645 from prometheus/cut-1204-pr1424
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bwplotka authored Oct 15, 2024
2 parents 05fcde9 + 504ad9b commit 48e12a1
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8 changes: 7 additions & 1 deletion CHANGELOG.md
Original file line number Diff line number Diff line change
@@ -1,5 +1,11 @@
## Unreleased

## 1.20.5 / 2024-10-15

* [BUGFIX] testutil: Reverted #1424; functions using compareMetricFamilies are (again) only failing if filtered metricNames are in the expected input.

## 1.20.4 / 2024-09-07

* [BUGFIX] histograms: Fix possible data race when appending exemplars vs metrics gather. #1623

## 1.20.3 / 2024-09-05
Expand Down Expand Up @@ -28,7 +34,7 @@
* [FEATURE] promlint: Add duplicated metric lint rule. #1472
* [BUGFIX] promlint: Relax metric type in name linter rule. #1455
* [BUGFIX] promhttp: Make sure server instrumentation wrapping supports new and future extra responseWriter methods. #1480
* [BUGFIX] testutil: Functions using compareMetricFamilies are now failing if filtered metricNames are not in the input. #1424
* [BUGFIX] **breaking** testutil: Functions using compareMetricFamilies are now failing if filtered metricNames are not in the input. #1424 (reverted in 1.20.5)

## 1.19.0 / 2024-02-27

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2 changes: 1 addition & 1 deletion VERSION
Original file line number Diff line number Diff line change
@@ -1 +1 @@
1.20.2
1.20.5
30 changes: 12 additions & 18 deletions prometheus/testutil/testutil.go
Original file line number Diff line number Diff line change
Expand Up @@ -158,6 +158,9 @@ func GatherAndCount(g prometheus.Gatherer, metricNames ...string) (int, error) {
// ScrapeAndCompare calls a remote exporter's endpoint which is expected to return some metrics in
// plain text format. Then it compares it with the results that the `expected` would return.
// If the `metricNames` is not empty it would filter the comparison only to the given metric names.
//
// NOTE: Be mindful of accidental discrepancies between expected and metricNames; metricNames filter
// both expected and scraped metrics. See https://github.com/prometheus/client_golang/issues/1351.
func ScrapeAndCompare(url string, expected io.Reader, metricNames ...string) error {
resp, err := http.Get(url)
if err != nil {
Expand Down Expand Up @@ -185,6 +188,9 @@ func ScrapeAndCompare(url string, expected io.Reader, metricNames ...string) err

// CollectAndCompare collects the metrics identified by `metricNames` and compares them in the Prometheus text
// exposition format to the data read from expected.
//
// NOTE: Be mindful of accidental discrepancies between expected and metricNames; metricNames filter
// both expected and collected metrics. See https://github.com/prometheus/client_golang/issues/1351.
func CollectAndCompare(c prometheus.Collector, expected io.Reader, metricNames ...string) error {
reg := prometheus.NewPedanticRegistry()
if err := reg.Register(c); err != nil {
Expand All @@ -197,6 +203,9 @@ func CollectAndCompare(c prometheus.Collector, expected io.Reader, metricNames .
// it to an expected output read from the provided Reader in the Prometheus text
// exposition format. If any metricNames are provided, only metrics with those
// names are compared.
//
// NOTE: Be mindful of accidental discrepancies between expected and metricNames; metricNames filter
// both expected and gathered metrics. See https://github.com/prometheus/client_golang/issues/1351.
func GatherAndCompare(g prometheus.Gatherer, expected io.Reader, metricNames ...string) error {
return TransactionalGatherAndCompare(prometheus.ToTransactionalGatherer(g), expected, metricNames...)
}
Expand All @@ -205,6 +214,9 @@ func GatherAndCompare(g prometheus.Gatherer, expected io.Reader, metricNames ...
// it to an expected output read from the provided Reader in the Prometheus text
// exposition format. If any metricNames are provided, only metrics with those
// names are compared.
//
// NOTE: Be mindful of accidental discrepancies between expected and metricNames; metricNames filter
// both expected and gathered metrics. See https://github.com/prometheus/client_golang/issues/1351.
func TransactionalGatherAndCompare(g prometheus.TransactionalGatherer, expected io.Reader, metricNames ...string) error {
got, done, err := g.Gather()
defer done()
Expand Down Expand Up @@ -277,15 +289,6 @@ func compareMetricFamilies(got, expected []*dto.MetricFamily, metricNames ...str
if metricNames != nil {
got = filterMetrics(got, metricNames)
expected = filterMetrics(expected, metricNames)
if len(metricNames) > len(got) {
var missingMetricNames []string
for _, name := range metricNames {
if ok := hasMetricByName(got, name); !ok {
missingMetricNames = append(missingMetricNames, name)
}
}
return fmt.Errorf("expected metric name(s) not found: %v", missingMetricNames)
}
}

return compare(got, expected)
Expand Down Expand Up @@ -327,12 +330,3 @@ func filterMetrics(metrics []*dto.MetricFamily, names []string) []*dto.MetricFam
}
return filtered
}

func hasMetricByName(metrics []*dto.MetricFamily, name string) bool {
for _, mf := range metrics {
if mf.GetName() == name {
return true
}
}
return false
}
136 changes: 46 additions & 90 deletions prometheus/testutil/testutil_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -328,46 +328,27 @@ func TestMetricNotFound(t *testing.T) {
}

func TestScrapeAndCompare(t *testing.T) {
scenarios := map[string]struct {
want string
metricNames []string
// expectedErr if empty, means no fail is expected for the comparison.
expectedErr string
}{
"empty metric Names": {
want: `
const expected = `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
some_total{ label1 = "value1" } 1
`,
metricNames: []string{},
},
"one metric": {
want: `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
`

some_total{ label1 = "value1" } 1
`,
metricNames: []string{"some_total"},
},
"multiple expected": {
want: `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
expectedReader := strings.NewReader(expected)

some_total{ label1 = "value1" } 1
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, expected)
}))
defer ts.Close()

# HELP some_total2 A value that represents a counter.
# TYPE some_total2 counter
if err := ScrapeAndCompare(ts.URL, expectedReader, "some_total"); err != nil {
t.Errorf("unexpected scraping result:\n%s", err)
}
}

some_total2{ label2 = "value2" } 1
`,
metricNames: []string{"some_total2"},
},
"expected metric name is not scraped": {
want: `
func TestScrapeAndCompareWithMultipleExpected(t *testing.T) {
const expected = `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
Expand All @@ -377,78 +358,53 @@ func TestScrapeAndCompare(t *testing.T) {
# TYPE some_total2 counter
some_total2{ label2 = "value2" } 1
`,
metricNames: []string{"some_total3"},
expectedErr: "expected metric name(s) not found: [some_total3]",
},
"one of multiple expected metric names is not scraped": {
want: `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
`

some_total{ label1 = "value1" } 1
expectedReader := strings.NewReader(expected)

# HELP some_total2 A value that represents a counter.
# TYPE some_total2 counter
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, expected)
}))
defer ts.Close()

some_total2{ label2 = "value2" } 1
`,
metricNames: []string{"some_total1", "some_total3"},
expectedErr: "expected metric name(s) not found: [some_total1 some_total3]",
},
}
for name, scenario := range scenarios {
t.Run(name, func(t *testing.T) {
expectedReader := strings.NewReader(scenario.want)

ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, scenario.want)
}))
defer ts.Close()
if err := ScrapeAndCompare(ts.URL, expectedReader, scenario.metricNames...); err != nil {
if scenario.expectedErr == "" || err.Error() != scenario.expectedErr {
t.Errorf("unexpected error happened: %s", err)
}
} else if scenario.expectedErr != "" {
t.Errorf("expected an error but got nil")
}
})
if err := ScrapeAndCompare(ts.URL, expectedReader, "some_total2"); err != nil {
t.Errorf("unexpected scraping result:\n%s", err)
}
}

t.Run("fetching fail", func(t *testing.T) {
err := ScrapeAndCompare("some_url", strings.NewReader("some expectation"), "some_total")
if err == nil {
t.Errorf("expected an error but got nil")
}
if !strings.HasPrefix(err.Error(), "scraping metrics failed") {
t.Errorf("unexpected error happened: %s", err)
}
})
func TestScrapeAndCompareFetchingFail(t *testing.T) {
err := ScrapeAndCompare("some_url", strings.NewReader("some expectation"), "some_total")
if err == nil {
t.Errorf("expected an error but got nil")
}
if !strings.HasPrefix(err.Error(), "scraping metrics failed") {
t.Errorf("unexpected error happened: %s", err)
}
}

t.Run("bad status code", func(t *testing.T) {
const expected = `
func TestScrapeAndCompareBadStatusCode(t *testing.T) {
const expected = `
# HELP some_total A value that represents a counter.
# TYPE some_total counter
some_total{ label1 = "value1" } 1
`

expectedReader := strings.NewReader(expected)
expectedReader := strings.NewReader(expected)

ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusBadGateway)
fmt.Fprintln(w, expected)
}))
defer ts.Close()
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusBadGateway)
fmt.Fprintln(w, expected)
}))
defer ts.Close()

err := ScrapeAndCompare(ts.URL, expectedReader, "some_total")
if err == nil {
t.Errorf("expected an error but got nil")
}
if !strings.HasPrefix(err.Error(), "the scraping target returned a status code other than 200") {
t.Errorf("unexpected error happened: %s", err)
}
})
err := ScrapeAndCompare(ts.URL, expectedReader, "some_total")
if err == nil {
t.Errorf("expected an error but got nil")
}
if !strings.HasPrefix(err.Error(), "the scraping target returned a status code other than 200") {
t.Errorf("unexpected error happened: %s", err)
}
}

func TestCollectAndCount(t *testing.T) {
Expand Down

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