From c7c7509669eaf604d0fa117579c6fc8b09b17210 Mon Sep 17 00:00:00 2001 From: leonnicolas <60091705+leonnicolas@users.noreply.github.com> Date: Wed, 15 May 2024 11:50:24 +0200 Subject: [PATCH] testutil compareMetricFamilies: make less error-prone (#1424) * testutil compareMetricFamilies: make less error-prone The functions `GatherAndCompare`, `ScrapeAndCompare` and others that use `compareMetricFamilies` under the hood can return no error if `metricNames` includes none of the names found in the scraped/gathered results. To avoid false Positves (an error being the negative case), we can return an error if there is is at least one name in `metricNames` that is not in the filtered results. Fixes: https://github.com/prometheus/client_golang/issues/1351 Signed-off-by: leonnicolas * Add missing metricNames to error In to see which metric names are missing, we can add them to the error message. Signed-off-by: leonnicolas * Apply suggestions from code review - remove if nil check - use two nested loops instead of map - use new function `hasMetricByName` for readability Co-authored-by: Bartlomiej Plotka Signed-off-by: leonnicolas <60091705+leonnicolas@users.noreply.github.com> * prometheus/testutil/testutil_test.go: compare complete error Before we would only compare the error prefix in `TestScrapeAndCompare`. Signed-off-by: leonnicolas --------- Signed-off-by: leonnicolas Signed-off-by: leonnicolas <60091705+leonnicolas@users.noreply.github.com> Co-authored-by: Bartlomiej Plotka --- prometheus/testutil/testutil.go | 18 ++++ prometheus/testutil/testutil_test.go | 140 ++++++++++++++++++--------- 2 files changed, 110 insertions(+), 48 deletions(-) diff --git a/prometheus/testutil/testutil.go b/prometheus/testutil/testutil.go index e818c2f..de7eaf1 100644 --- a/prometheus/testutil/testutil.go +++ b/prometheus/testutil/testutil.go @@ -277,6 +277,15 @@ 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) @@ -318,3 +327,12 @@ 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 +} diff --git a/prometheus/testutil/testutil_test.go b/prometheus/testutil/testutil_test.go index 06e3677..ec835a6 100644 --- a/prometheus/testutil/testutil_test.go +++ b/prometheus/testutil/testutil_test.go @@ -328,27 +328,32 @@ func TestMetricNotFound(t *testing.T) { } func TestScrapeAndCompare(t *testing.T) { - const expected = ` + 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: ` # 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 - expectedReader := strings.NewReader(expected) - - ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { - fmt.Fprintln(w, expected) - })) - defer ts.Close() - - if err := ScrapeAndCompare(ts.URL, expectedReader, "some_total"); err != nil { - t.Errorf("unexpected scraping result:\n%s", err) - } -} - -func TestScrapeAndCompareWithMultipleExpected(t *testing.T) { - const expected = ` + 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 @@ -358,53 +363,92 @@ func TestScrapeAndCompareWithMultipleExpected(t *testing.T) { # TYPE some_total2 counter some_total2{ label2 = "value2" } 1 - ` + `, + metricNames: []string{"some_total2"}, + }, + "expected metric name is not scraped": { + 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_total2"); err != nil { - t.Errorf("unexpected scraping result:\n%s", err) + 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 + + # HELP some_total2 A value that represents a counter. + # TYPE some_total2 counter + + 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) -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") + 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 !strings.HasPrefix(err.Error(), "scraping metrics failed") { - t.Errorf("unexpected error happened: %s", err) - } -} -func TestScrapeAndCompareBadStatusCode(t *testing.T) { - const expected = ` + 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) + } + }) + + t.Run("bad status code", func(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) {