// startingGroup returns a tagset that only has tags from `original` that are found in `tags`.
func startingGroup(original api.TagSet, tags []string) api.TagSet {
result := api.NewTagSet()
for _, tag := range tags {
result[tag] = original[tag]
}
return result
}
// setTagSeries returns a copy of the timeseries where the given `newTag` has been set to `newValue`, or added if it wasn't present.
func setTagSeries(series api.Timeseries, newTag string, newValue string) api.Timeseries {
tagSet := api.NewTagSet()
for tag, val := range series.TagSet {
tagSet[tag] = val
}
tagSet[newTag] = newValue
series.TagSet = tagSet
return series
}
// dropTagSeries returns a copy of the timeseries where the given `dropTag` has been removed from its TagSet.
func dropTagSeries(series api.Timeseries, dropTag string) api.Timeseries {
tagSet := api.NewTagSet()
for tag, val := range series.TagSet {
if tag != dropTag {
tagSet[tag] = val
}
}
series.TagSet = tagSet
return series
}
func (b movingAverageBackend) FetchSingleTimeseries(r api.FetchTimeseriesRequest) (api.Timeseries, error) {
t := r.Timerange
values := []float64{9, 2, 1, 6, 4, 5}
startIndex := t.Start()/100 - 10
result := make([]float64, t.Slots())
for i := range result {
result[i] = values[i+int(startIndex)]
}
return api.Timeseries{Values: values, TagSet: api.NewTagSet()}, nil
}
// startingCollapse returns a tagset copy of `original` but with all tags in `tags` deleted.
func startingCollase(original api.TagSet, tags []string) api.TagSet {
result := api.NewTagSet()
for tag, value := range original {
result[tag] = value
}
for _, tagToDelete := range tags {
delete(result, tagToDelete)
}
return result
}
func (value ScalarValue) ToSeriesList(timerange api.Timerange) (api.SeriesList, error) {
series := make([]float64, timerange.Slots())
for i := range series {
series[i] = float64(value)
}
return api.SeriesList{
Series: []api.Timeseries{api.Timeseries{Values: series, TagSet: api.NewTagSet()}},
Timerange: timerange,
}, nil
}
func TestMovingAverage(t *testing.T) {
fakeAPI := mocks.NewFakeMetricMetadataAPI()
fakeAPI.AddPairWithoutGraphite(api.TaggedMetric{"series", api.NewTagSet()})
fakeBackend := movingAverageBackend{}
timerange, err := api.NewTimerange(1200, 1500, 100)
if err != nil {
t.Fatalf(err.Error())
}
expression := &functionExpression{
functionName: "transform.moving_average",
groupBy: []string{},
arguments: []function.Expression{
&metricFetchExpression{"series", api.TruePredicate},
durationExpression{"300ms", 300 * time.Millisecond},
},
}
backend := fakeBackend
result, err := evaluateToSeriesList(expression,
&function.EvaluationContext{
MetricMetadataAPI: fakeAPI,
TimeseriesStorageAPI: backend,
Timerange: timerange,
SampleMethod: api.SampleMean,
FetchLimit: function.NewFetchCounter(1000),
Registry: registry.Default(),
Cancellable: api.NewCancellable(),
OptimizationConfiguration: optimize.NewOptimizationConfiguration(),
})
if err != nil {
t.Errorf(err.Error())
}
expected := []float64{4, 3, 11.0 / 3, 5}
if len(result.Series) != 1 {
t.Fatalf("expected exactly 1 returned series")
}
if len(result.Series[0].Values) != len(expected) {
t.Fatalf("expected exactly %d values in returned series, but got %d", len(expected), len(result.Series[0].Values))
}
const eps = 1e-7
for i := range expected {
if math.Abs(result.Series[0].Values[i]-expected[i]) > eps {
t.Fatalf("expected %+v but got %+v", expected, result.Series[0].Values)
}
}
}
func Test_ParallelMultiBackend_Success(t *testing.T) {
a := assert.New(t)
suite := newSuite()
defer suite.cleanup()
go func() {
_, err := suite.multiBackend.FetchMultipleSeries(api.FetchMultipleRequest{
Metrics: []api.TaggedMetric{api.TaggedMetric{"a", api.NewTagSet()}},
Cancellable: suite.cancellable,
})
a.CheckError(err)
suite.waitGroup.Done()
}()
suite.backend.tickets <- struct{}{}
suite.waitGroup.Wait()
}
// extractTagValues extracts the tagset using the given regex and the list of tags.
func extractTagValues(regex *regexp.Regexp, tagList []string, input string) api.TagSet {
matches := regex.FindStringSubmatch(input)
if matches == nil {
return nil
}
tagSet := api.NewTagSet()
for index, tagValue := range matches {
if index == 0 {
continue
}
tagKey := tagList[index-1]
tagSet[tagKey] = tagValue
}
return tagSet
}
func TestMovingAverage(t *testing.T) {
fakeAPI := mocks.NewFakeApi()
fakeAPI.AddPair(api.TaggedMetric{"series", api.NewTagSet()}, "series")
fakeBackend := movingAverageBackend{}
timerange, err := api.NewTimerange(1200, 1500, 100)
if err != nil {
t.Fatalf(err.Error())
}
expression := &functionExpression{
functionName: "transform.moving_average",
groupBy: []string{},
arguments: []function.Expression{
&metricFetchExpression{"series", api.TruePredicate},
stringExpression{"300ms"},
},
}
result, err := evaluateToSeriesList(expression,
function.EvaluationContext{
API: fakeAPI,
MultiBackend: backend.NewSequentialMultiBackend(fakeBackend),
Timerange: timerange,
SampleMethod: api.SampleMean,
FetchLimit: function.NewFetchCounter(1000),
Registry: registry.Default(),
})
if err != nil {
t.Errorf(err.Error())
}
expected := []float64{4, 3, 11.0 / 3, 5}
if len(result.Series) != 1 {
t.Fatalf("expected exactly 1 returned series")
}
if len(result.Series[0].Values) != len(expected) {
t.Fatalf("expected exactly %d values in returned series", len(expected))
}
const eps = 1e-7
for i := range expected {
if math.Abs(result.Series[0].Values[i]-expected[i]) > eps {
t.Fatalf("expected %+v but got %+v", expected, result.Series[0].Values)
}
}
}
func TestCaching(t *testing.T) {
optimizer := NewOptimizationConfiguration()
optimizer.EnableMetricMetadataCaching = true
updateFunc := func() ([]api.TagSet, error) {
// map[string]string
result := []api.TagSet{api.NewTagSet()}
return result, nil
}
someMetric := api.MetricKey("blah")
optimizer.AllTagsCacheHitOrExecute(someMetric, updateFunc)
updateFunc = func() ([]api.TagSet, error) {
t.Errorf("Should not be called")
return nil, nil
}
optimizer.AllTagsCacheHitOrExecute(someMetric, updateFunc)
}
func Test_ScalarExpression(t *testing.T) {
timerangeA, err := api.NewTimerange(0, 10, 2)
if err != nil {
t.Fatalf("invalid timerange used for testcase")
return
}
for _, test := range []struct {
expr scalarExpression
timerange api.Timerange
expectedSeries []api.Timeseries
}{
{
scalarExpression{5},
timerangeA,
[]api.Timeseries{
api.Timeseries{
Values: []float64{5.0, 5.0, 5.0, 5.0, 5.0, 5.0},
TagSet: api.NewTagSet(),
},
},
},
} {
a := assert.New(t).Contextf("%+v", test)
result, err := evaluateToSeriesList(test.expr, &function.EvaluationContext{
TimeseriesStorageAPI: FakeBackend{},
Timerange: test.timerange,
SampleMethod: api.SampleMean,
FetchLimit: function.NewFetchCounter(1000),
Registry: registry.Default(),
})
if err != nil {
t.Fatalf("failed to convert number into serieslist")
}
a.EqInt(len(result.Series), len(test.expectedSeries))
for i := 0; i < len(result.Series); i++ {
a.Eq(result.Series[i].Values, test.expectedSeries[i].Values)
}
}
}
// This method takes a partial joinrow, and evaluates the validity of appending `series` to it.
// If this is possible, return the new series and true; otherwise return false for "ok"
func extendRow(row JoinRow, series api.Timeseries) (JoinRow, bool) {
for key, newValue := range series.TagSet {
oldValue, ok := map[string]string(row.TagSet)[key]
if ok && newValue != oldValue {
// If this occurs, then the candidate member (series) and the rest of the row are in
// conflict about `key`, since they assign it different values. If this occurs, then
// it is not possible to assign any key here.
return JoinRow{}, false
}
}
// if this point has been reached, then it is possible to extend the row without conflict
newTagSet := api.NewTagSet()
result := JoinRow{newTagSet, append(row.Row, series)}
for key, newValue := range series.TagSet {
newTagSet[key] = newValue
}
for key, oldValue := range row.TagSet {
newTagSet[key] = oldValue
}
return result, true
}
func Test_ParallelMultiBackend_Timeout(t *testing.T) {
a := assert.New(t)
suite := newSuite()
defer suite.cleanup()
go func() {
_, err := suite.multiBackend.FetchMultipleSeries(api.FetchMultipleRequest{
Metrics: []api.TaggedMetric{api.TaggedMetric{"a", api.NewTagSet()}},
Cancellable: suite.cancellable,
})
if err == nil {
t.Errorf("Error expected, but got nil")
} else {
casted, ok := err.(api.BackendError)
if !ok {
t.Errorf("Invalid error type")
} else {
a.Eq(casted.Code, api.FetchTimeoutError)
}
}
suite.waitGroup.Done()
}()
close(suite.cancellable.Done())
suite.waitGroup.Wait()
}
// Join generates a cartesian product of the given series lists, and then returns rows where the tags are matching.
func Join(lists []api.SeriesList) JoinResult {
// place an empty row inside the results list first
// this row will be used to build up all others
emptyRow := JoinRow{api.NewTagSet(), []api.Timeseries{}}
results := []JoinRow{emptyRow}
// The `results` list is given an inductive definition:
// at the end of the `i`th iteration of the outer loop,
// `results` corresponds to the join of the first `i` seriesLists given as input
for _, list := range lists {
next := []JoinRow{}
// `next` is gradually accumulated into the final join of the first `i` (iteration) seriesLists
// results already contains the join of the the first (i-1)th series
for _, series := range list.Series {
// here we have our series
// iterator over the results of the previous iteration:
for _, previous := range results {
// consider adding this series to each row from the joins of all previous series lists
// if this is successful, the newly extended list is added to the `next` slice
extension, ok := extendRow(previous, series)
if ok {
next = append(next, extension)
}
}
}
// `next` now contains the join of the first `i` iterations,
// while `results` contains the join of the first `i-1` iterations.
results = next
// thus we update `results`
}
// at this stage, iteration has continued over the entire set of lists,
// so `results` contains the join of all of the lists.
return JoinResult{Rows: results}
}
func TestCacheExpiration(t *testing.T) {
optimizer := NewOptimizationConfiguration()
optimizer.EnableMetricMetadataCaching = true
latch := false
updateFunc := func() ([]api.TagSet, error) {
// map[string]string
latch = true
result := []api.TagSet{api.NewTagSet()}
return result, nil
}
someMetric := api.MetricKey("blah")
optimizer.AllTagsCacheHitOrExecute(someMetric, updateFunc)
if !latch {
t.Errorf("We expected the update function to be called, but it wasn't")
}
optimizer.TimeSourceForNow = func() time.Time { return time.Now().Add(5 * time.Hour) }
latch = false // Reset the latch
optimizer.AllTagsCacheHitOrExecute(someMetric, updateFunc)
if !latch {
t.Errorf("We expected the update function to be called, but it wasn't")
}
}
func (expr *LiteralExpression) Evaluate(context *function.EvaluationContext) (function.Value, error) {
return api.SeriesList{
Series: []api.Timeseries{api.Timeseries{Values: expr.Values, TagSet: api.NewTagSet()}},
Timerange: api.Timerange{},
}, nil
}
func (a fakeAPI) ToTaggedName(metric api.GraphiteMetric) (api.TaggedMetric, error) {
return api.TaggedMetric{
MetricKey: api.MetricKey(metric),
TagSet: api.NewTagSet(),
}, nil
}
func TestCommand_Select(t *testing.T) {
epsilon := 1e-10
fakeApi := mocks.NewFakeApi()
fakeApi.AddPair(api.TaggedMetric{"series_1", api.ParseTagSet("dc=west")}, emptyGraphiteName)
fakeApi.AddPair(api.TaggedMetric{"series_2", api.ParseTagSet("dc=east")}, emptyGraphiteName)
fakeApi.AddPair(api.TaggedMetric{"series_2", api.ParseTagSet("dc=west")}, emptyGraphiteName)
fakeApi.AddPair(api.TaggedMetric{"series_3", api.ParseTagSet("dc=west")}, emptyGraphiteName)
fakeApi.AddPair(api.TaggedMetric{"series_3", api.ParseTagSet("dc=east")}, emptyGraphiteName)
fakeApi.AddPair(api.TaggedMetric{"series_3", api.ParseTagSet("dc=north")}, emptyGraphiteName)
fakeApi.AddPair(api.TaggedMetric{"series_timeout", api.ParseTagSet("dc=west")}, emptyGraphiteName)
var fakeBackend fakeApiBackend
testTimerange, err := api.NewTimerange(0, 120, 30)
if err != nil {
t.Errorf("Invalid test timerange")
return
}
earlyTimerange, err := api.NewTimerange(0, 60, 30)
if err != nil {
t.Errorf("Invalid test timerange")
}
lateTimerange, err := api.NewTimerange(60, 120, 30)
if err != nil {
t.Errorf("Invalid test timerange")
}
for _, test := range []struct {
query string
expectError bool
expected api.SeriesList
}{
{"select does_not_exist from 0 to 120 resolution 30ms", true, api.SeriesList{}},
{"select series_1 from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{1, 2, 3, 4, 5},
api.ParseTagSet("dc=west"),
}},
Timerange: testTimerange,
Name: "series_1",
}},
{"select series_timeout from 0 to 120 resolution 30ms", true, api.SeriesList{}},
{"select series_1 + 1 from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{2, 3, 4, 5, 6},
api.ParseTagSet("dc=west"),
}},
Timerange: testTimerange,
Name: "",
}},
{"select series_1 * 2 from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{2, 4, 6, 8, 10},
api.ParseTagSet("dc=west"),
}},
Timerange: testTimerange,
Name: "",
}},
{"select aggregate.max(series_2) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{3, 2, 3, 6, 5},
api.NewTagSet(),
}},
Timerange: testTimerange,
Name: "series_2",
}},
{"select (1 + series_2) | aggregate.max from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{4, 3, 4, 7, 6},
api.NewTagSet(),
}},
Timerange: testTimerange,
Name: "series_2",
}},
{"select series_1 from 0 to 60 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{1, 2, 3},
api.ParseTagSet("dc=west"),
}},
Timerange: earlyTimerange,
Name: "series_1",
}},
{"select transform.timeshift(series_1,31ms) from 0 to 60 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{2, 3, 4},
api.ParseTagSet("dc=west"),
}},
Timerange: earlyTimerange,
Name: "series_1",
}},
{"select transform.timeshift(series_1,62ms) from 0 to 60 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{3, 4, 5},
api.ParseTagSet("dc=west"),
}},
Timerange: earlyTimerange,
Name: "series_1",
}},
{"select transform.timeshift(series_1,29ms) from 0 to 60 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{2, 3, 4},
api.ParseTagSet("dc=west"),
}},
Timerange: earlyTimerange,
Name: "series_1",
}},
{"select transform.timeshift(series_1,-31ms) from 60 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{2, 3, 4},
api.ParseTagSet("dc=west"),
}},
Timerange: lateTimerange,
Name: "series_1",
}},
{"select transform.timeshift(series_1,-29ms) from 60 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{{
[]float64{2, 3, 4},
api.ParseTagSet("dc=west"),
}},
Timerange: lateTimerange,
Name: "series_1",
}},
{"select series_3 from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
},
}},
{"select series_3 | filter.recent_highest_max(3, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
},
}},
{"select series_3 | filter.recent_highest_max(2, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
},
}},
{"select series_3 | filter.recent_highest_max(1, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(3, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(4, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
},
}},
{"select series_3 | filter.recent_highest_max(70, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(2, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(1, 30ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
},
}},
{"select series_3 | filter.recent_highest_max(3, 3000ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
},
}},
{"select series_3 | filter.recent_highest_max(2, 3000ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
},
}},
{"select series_3 | filter.recent_highest_max(1, 3000ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(3, 3000ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
{
[]float64{5, 5, 5, 2, 2},
api.ParseTagSet("dc=east"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(2, 3000ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
{
[]float64{1, 1, 1, 4, 4},
api.ParseTagSet("dc=west"),
},
},
}},
{"select series_3 | filter.recent_lowest_max(1, 3000ms) from 0 to 120 resolution 30ms", false, api.SeriesList{
Series: []api.Timeseries{
{
[]float64{3, 3, 3, 3, 3},
api.ParseTagSet("dc=north"),
},
},
}},
{"select series_1 from -1000d to now resolution 30s", true, api.SeriesList{}},
} {
a := assert.New(t).Contextf("query=%s", test.query)
expected := test.expected
command, err := Parse(test.query)
if err != nil {
a.Errorf("Unexpected error while parsing")
continue
}
a.EqString(command.Name(), "select")
rawResult, err := command.Execute(ExecutionContext{
Backend: backend.NewSequentialMultiBackend(fakeBackend),
API: fakeApi,
FetchLimit: 1000,
Timeout: 10 * time.Millisecond,
})
if err != nil {
if !test.expectError {
a.Errorf("Unexpected error while executing: %s", err.Error())
}
} else {
casted := rawResult.([]function.Value)
actual, _ := casted[0].ToSeriesList(api.Timerange{})
a.EqInt(len(actual.Series), len(expected.Series))
if len(actual.Series) == len(expected.Series) {
for i := 0; i < len(expected.Series); i++ {
a.Eq(actual.Series[i].TagSet, expected.Series[i].TagSet)
actualLength := len(actual.Series[i].Values)
expectedLength := len(actual.Series[i].Values)
a.Eq(actualLength, expectedLength)
if actualLength == expectedLength {
for j := 0; j < actualLength; j++ {
a.EqFloat(actual.Series[i].Values[j], expected.Series[i].Values[j], epsilon)
}
}
}
}
}
}
// Test that the limit is correct
command, err := Parse("select series_1, series_2 from 0 to 120 resolution 30ms")
if err != nil {
t.Fatalf("Unexpected error while parsing")
return
}
context := ExecutionContext{Backend: backend.NewSequentialMultiBackend(fakeBackend), API: fakeApi, FetchLimit: 3, Timeout: 0}
_, err = command.Execute(context)
if err != nil {
t.Fatalf("expected success with limit 3 but got err = %s", err.Error())
return
}
context.FetchLimit = 2
_, err = command.Execute(context)
if err == nil {
t.Fatalf("expected failure with limit = 2")
return
}
command, err = Parse("select series2 from 0 to 120 resolution 30ms")
if err != nil {
t.Fatalf("Unexpected error while parsing")
return
}
_, err = command.Execute(context)
if err != nil {
t.Fatalf("expected success with limit = 2 but got %s", err.Error())
}
}