Merge pull request #312 from jbub/data-file-empty-panic

Avoid panic on empty file provided by --data-file.

runner/data.go

@@ -141,7 +141,7 @@ func (dp *dataProvider) getDataForCall(ctd *CallData) ([]*dynamic.Message, error
 		return nil, err
 	}
 
-	if !dp.mtd.IsClientStreaming() {
+	if !dp.mtd.IsClientStreaming() && len(inputs) > 0 {
 		inputIdx := int(ctd.RequestNumber % int64(len(inputs)))
 		unaryInput := inputs[inputIdx]
 

runner/run_test.go

@@ -3171,6 +3171,39 @@ func TestRunWrappedUnary(t *testing.T) {
 		assert.Equal(t, report.Average, report.Slowest)
 		assert.Equal(t, report.Average, report.Fastest)
 	})
+
+	t.Run("json string data from empty file", func(t *testing.T) {
+		report, err := Run(
+			"wrapped.WrappedService.GetMessage",
+			internal.TestLocalhost,
+			WithProtoFile("../testdata/wrapped.proto", []string{"../testdata"}),
+			WithDataFromFile(`../testdata/data_empty.json`),
+			WithInsecure(true),
+		)
+
+		assert.Error(t, err)
+
+		assert.NotNil(t, report)
+
+		assert.Equal(t, 0, int(report.Count))
+		assert.Zero(t, report.Average)
+		assert.Zero(t, report.Fastest)
+		assert.Zero(t, report.Slowest)
+		assert.Zero(t, report.Rps)
+		assert.Empty(t, report.Name)
+		assert.NotEmpty(t, report.Date)
+		assert.NotEmpty(t, report.Options)
+		assert.Empty(t, report.Details)
+		assert.Equal(t, true, report.Options.Insecure)
+		assert.Empty(t, report.LatencyDistribution)
+		assert.Equal(t, ReasonNormalEnd, report.EndReason)
+		assert.Empty(t, report.ErrorDist)
+
+		assert.Equal(t, report.Average, report.Slowest)
+		assert.Equal(t, report.Average, report.Fastest)
+	})
+
+
 }
 
 func TestRunGtimeUnary(t *testing.T) {