Fix some messages and tests

libbeat/processors/actions/extract_field.go

@@ -57,18 +57,18 @@ func NewExtractField(c common.Config) (processors.Processor, error) {
 func (f extract_field) Run(event common.MapStr) (common.MapStr, error) {
 	fieldValue, err := event.GetValue(f.Field)
 	if err != nil {
-		return nil, fmt.Errorf("Error getting field '%s' from event", f.Field)
+		return nil, fmt.Errorf("error getting field '%s' from event", f.Field)
 	}
 
 	value, ok := fieldValue.(string)
 	if !ok {
-		return nil, fmt.Errorf("Could not get a string from field '%s'", f.Field)
+		return nil, fmt.Errorf("could not get a string from field '%s'", f.Field)
 	}
 
 	parts := strings.Split(value, f.Separator)
 	parts = deleteEmpty(parts)
 	if len(parts) < f.Index+1 {
-		return nil, fmt.Errorf("Index is out of range for field '%s'", f.Field)
+		return nil, fmt.Errorf("index is out of range for field '%s'", f.Field)
 	}
 
 	event.Put(f.Target, parts[f.Index])

libbeat/processors/actions/extract_field_test.go

@@ -64,7 +64,9 @@ func TestCommonPaths(t *testing.T) {
 		actual := runExtractField(t, testConfig, input)
 
 		result, err := actual.GetValue(test.Target)
-		assert.NoError(t, err)
+		if err != nil {
+			t.Fatalf("could not get target field: %s", err)
+		}
 		assert.Equal(t, result.(string), test.Result)
 	}
 }
@@ -76,12 +78,13 @@ func runExtractField(t *testing.T, config *common.Config, input common.MapStr) c
 
 	p, err := NewExtractField(*config)
 	if err != nil {
-		logp.Err("Error initializing decode_json_fields")
-		t.Fatal(err)
+		t.Fatalf("error initializing extract_field: %s", err)
 	}
 
 	actual, err := p.Run(input)
-	assert.NoError(t, err)
+	if err != nil {
+		t.Fatalf("error running extract_field: %s", err)
+	}
 
 	return actual
 }