Merge pull request #174 from grafana/feature/skip-report-if-not-enoug…

…ht-data

fix: Skipping HTML report file generation if there is not enough data.

dashboard/extension_test.go

@@ -271,6 +271,8 @@ func TestExtension_report(t *testing.T) {
 		ext.AddMetricSamples(testSampleContainer(t, sample).toArray())
 	}()
 
+	time.Sleep(100 * time.Millisecond)
+
 	assert.NoError(t, ext.Stop())
 
 	st, err := osFS.Stat(file.Name() + ".gz")
@@ -282,6 +284,36 @@ func TestExtension_report(t *testing.T) {
 	assert.NoError(t, osFS.Remove(file.Name()+".gz"))
 }
 
+func TestExtension_skip_report(t *testing.T) {
+	t.Parallel()
+
+	osFS := fsext.NewMemMapFs()
+
+	file, err := osFS.Create("temp")
+
+	assert.NoError(t, err)
+	assert.NoError(t, file.Close())
+
+	var params output.Params
+
+	params.Logger = logrus.StandardLogger()
+	params.ConfigArgument = "period=10ms&port=-1&report=" + file.Name() + ".gz"
+	params.FS = osFS
+
+	ext, err := New(params)
+
+	assert.NoError(t, err)
+	assert.NotNil(t, ext)
+
+	assert.NoError(t, ext.Start())
+
+	assert.NoError(t, ext.Stop())
+
+	_, err = osFS.Stat(file.Name() + ".gz")
+
+	assert.Error(t, err)
+}
+
 func Test_newParamData(t *testing.T) {
 	t.Parallel()
 

dashboard/report.go

@@ -24,6 +24,8 @@ type reporter struct {
 	data   *reportData
 	output string
 	mu     sync.RWMutex
+
+	snapshotCount int
 }
 
 var (
@@ -51,6 +53,13 @@ func (rep *reporter) onStop(_ error) error {
 		return nil
 	}
 
+	if rep.snapshotCount < 2 {
+		rep.proc.logger.Warn(
+			"The test run was short, report generation was skipped (not enough data)",
+		)
+		return nil
+	}
+
 	file, err := rep.proc.fs.Create(rep.output)
 	if err != nil {
 		return err
@@ -105,6 +114,12 @@ func (rep *reporter) onEvent(name string, data interface{}) {
 		}
 
 		rep.proc.logger.Error(err)
+
+		return
+	}
+
+	if name == snapshotEvent {
+		rep.snapshotCount++
 	}
 }