add mustB64dec (and mustB32dec) which fails on bad b64 data instead o…

…f decoding to "illegal base64 data at input byte ..."

Closes Masterminds#417

docs/encoding.md

@@ -4,3 +4,4 @@ Sprig has the following encoding and decoding functions:
 
 - `b64enc`/`b64dec`: Encode or decode with Base64
 - `b32enc`/`b32dec`: Encode or decode with Base32
+- `mustB32dec`/`mustB64dec`: will return an error in case data is not valid encoded data.

functions.go

@@ -288,10 +288,12 @@ var genericMap = map[string]interface{}{
 	"osIsAbs": filepath.IsAbs,
 
 	// Encoding:
-	"b64enc": base64encode,
-	"b64dec": base64decode,
-	"b32enc": base32encode,
-	"b32dec": base32decode,
+	"b64enc":     base64encode,
+	"b64dec":     base64decode,
+	"mustB64dec": mustBase64decode,
+	"b32enc":     base32encode,
+	"b32dec":     base32decode,
+	"mustB32dec": mustBase32decode,
 
 	// Data Structures:
 	"tuple":              list, // FIXME: with the addition of append/prepend these are no longer immutable.

strings.go

@@ -16,23 +16,39 @@ func base64encode(v string) string {
 }
 
 func base64decode(v string) string {
-	data, err := base64.StdEncoding.DecodeString(v)
+	data, err := mustBase64decode(v)
 	if err != nil {
 		return err.Error()
 	}
-	return string(data)
+	return data
+}
+
+func mustBase64decode(v string) (string, error) {
+	data, err := base64.StdEncoding.DecodeString(v)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
 }
 
 func base32encode(v string) string {
 	return base32.StdEncoding.EncodeToString([]byte(v))
 }
 
 func base32decode(v string) string {
-	data, err := base32.StdEncoding.DecodeString(v)
+	data, err := mustBase32decode(v)
 	if err != nil {
 		return err.Error()
 	}
-	return string(data)
+	return data
+}
+
+func mustBase32decode(v string) (string, error) {
+	data, err := base32.StdEncoding.DecodeString(v)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
 }
 
 func abbrev(width int, s string) string {

strings_test.go

@@ -154,6 +154,7 @@ func TestSortAlpha(t *testing.T) {
 		assert.NoError(t, runt(tpl, expect))
 	}
 }
+
 func TestBase64EncodeDecode(t *testing.T) {
 	magicWord := "coffee"
 	expect := base64.StdEncoding.EncodeToString([]byte(magicWord))
@@ -171,6 +172,32 @@ func TestBase64EncodeDecode(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestBase64DecodeErr(t *testing.T) {
+	expect := "illegal base64 data at input byte 4"
+
+	tpl := `{{b64dec "coffee"}}`
+	if err := runt(tpl, expect); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestMustBase64Decode(t *testing.T) {
+	expect := "coffee"
+	b64data := base64.StdEncoding.EncodeToString([]byte(expect))
+
+	tpl := fmt.Sprintf("{{mustB64dec %q}}", b64data)
+	if err := runt(tpl, expect); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestMustBase64DecodeErr(t *testing.T) {
+	tpl := `{{mustB64dec "coffee"}}`
+	_, err := runRaw(tpl, nil)
+	assert.EqualError(t, err, `template: test:1:2: executing "test" at <mustB64dec "coffee">: error calling mustB64dec: illegal base64 data at input byte 4`)
+}
+
 func TestBase32EncodeDecode(t *testing.T) {
 	magicWord := "coffee"
 	expect := base32.StdEncoding.EncodeToString([]byte(magicWord))
@@ -189,6 +216,31 @@ func TestBase32EncodeDecode(t *testing.T) {
 	}
 }
 
+func TestBase32DecodeErr(t *testing.T) {
+	expect := "illegal base32 data at input byte 0"
+
+	tpl := `{{b32dec "coffee"}}`
+	if err := runt(tpl, expect); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestMustBase32Decode(t *testing.T) {
+	expect := "coffee"
+	b32data := base32.StdEncoding.EncodeToString([]byte(expect))
+
+	tpl := fmt.Sprintf("{{mustB32dec %q}}", b32data)
+	if err := runt(tpl, expect); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestMustBase32DecodeErr(t *testing.T) {
+	tpl := `{{mustB32dec "coffee"}}`
+	_, err := runRaw(tpl, nil)
+	assert.EqualError(t, err, `template: test:1:2: executing "test" at <mustB32dec "coffee">: error calling mustB32dec: illegal base32 data at input byte 0`)
+}
+
 func TestGoutils(t *testing.T) {
 	tests := map[string]string{
 		`{{abbrev 5 "hello world"}}`:           "he...",