text/template: better error messages during execution,
They now show the correct name, the byte offset on the line, and context for the failed evaluation.
Before:
template: three:7: error calling index: index out of range: 5
After:
template: top:7:20: executing "three" at <index "hi" $>: error calling index: index out of range: 5
Here top is the template that was parsed to create the set, and the error appears with the action
starting at byte 20 of line 7 of "top", inside the template called "three", evaluating the expression
<index "hi" $>.
Also fix a bug in index: it didn't work on strings. Ouch.
Also fix bug in error for index: was showing type of index not slice.
The real previous error was:
template: three:7: error calling index: can't index item of type int
The html/template package's errors can be improved by building on this;
I'll do that in a separate pass.
Extends the API for text/template/parse but only by addition of a field and method. The
old API still works.
Fixes #3188.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6576058
diff --git a/src/pkg/text/template/exec_test.go b/src/pkg/text/template/exec_test.go
index 0835d31..d793651 100644
--- a/src/pkg/text/template/exec_test.go
+++ b/src/pkg/text/template/exec_test.go
@@ -675,6 +675,32 @@
}
}
+const execErrorText = `line 1
+line 2
+line 3
+{{template "one" .}}
+{{define "one"}}{{template "two" .}}{{end}}
+{{define "two"}}{{template "three" .}}{{end}}
+{{define "three"}}{{index "hi" $}}{{end}}`
+
+// Check that an error from a nested template contains all the relevant information.
+func TestExecError(t *testing.T) {
+ tmpl, err := New("top").Parse(execErrorText)
+ if err != nil {
+ t.Fatal("parse error:", err)
+ }
+ var b bytes.Buffer
+ err = tmpl.Execute(&b, 5) // 5 is out of range indexing "hi"
+ if err == nil {
+ t.Fatal("expected error")
+ }
+ const want = `template: top:7:20: executing "three" at <index "hi" $>: error calling index: index out of range: 5`
+ got := err.Error()
+ if got != want {
+ t.Errorf("expected\n%q\ngot\n%q", want, got)
+ }
+}
+
func TestJSEscaping(t *testing.T) {
testCases := []struct {
in, exp string
