- Changed error behaviour to returning an error instead of writing the error in the template

- Added tests for using a function inside a template that is evaluated using the "tpl" function

pkg/engine/engine.go

@@ -162,7 +162,7 @@ func (e *Engine) alterFuncMap(t *template.Template) template.FuncMap {
 	}
 
 	// Add the 'tpl' function here
-	funcMap["tpl"] = func(tpl string, vals chartutil.Values) string {
+	funcMap["tpl"] = func(tpl string, vals chartutil.Values) (string, error) {
 		r := renderable{
 			tpl:  tpl,
 			vals: vals,
@@ -173,9 +173,9 @@ func (e *Engine) alterFuncMap(t *template.Template) template.FuncMap {
 
 		result, err := e.render(templates)
 		if err != nil {
-			return fmt.Errorf("Error during tpl function execution for %q", tpl).Error()
+			return "", fmt.Errorf("Error during tpl function execution for %q: %s", tpl, err.Error())
 		}
-		return result["template"]
+		return result["template"], nil
 	}
 
 	return funcMap

pkg/engine/engine_test.go

@@ -474,4 +474,33 @@ func TestAlterFuncMap(t *testing.T) {
 		t.Errorf("Expected %q, got %q (%v)", expectTplStr, gotStrTpl, outTpl)
 	}
 
+	tplChartWithFunction := &chart.Chart{
+		Metadata: &chart.Metadata{Name: "TplFunction"},
+		Templates: []*chart.Template{
+			{Name: "templates/base", Data: []byte(`Evaluate tpl {{tpl "Value: {{ .Values.value | quote}}" .}}`)},
+		},
+		Values:       &chart.Config{Raw: ``},
+		Dependencies: []*chart.Chart{},
+	}
+
+	tplValuesWithFunction := chartutil.Values{
+		"Values": chartutil.Values{
+			"value": "myvalue",
+		},
+		"Chart": tplChartWithFunction.Metadata,
+		"Release": chartutil.Values{
+			"Name": "TestRelease",
+		},
+	}
+
+	outTplWithFunction, err := New().Render(tplChartWithFunction, tplValuesWithFunction)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expectTplStrWithFunction := "Evaluate tpl Value: \"myvalue\""
+	if gotStrTplWithFunction := outTplWithFunction["TplFunction/templates/base"]; gotStrTplWithFunction != expectTplStrWithFunction {
+		t.Errorf("Expected %q, got %q (%v)", expectTplStrWithFunction, gotStrTplWithFunction, outTplWithFunction)
+	}
+
 }