Added unit tests, documentation and function descriptions across the board. Increased cyclop complexity threshold to 15 which is a bit more sane than 10 and excluded _test.go files from linters.

internal/config/section.go

@@ -205,6 +205,9 @@ func setValue(ptr any, key string, value any) error {
 	return setField(section, f, value)
 }
 
+// setField converts value to the field's type and, if the section has a
+// validator, checks it, before setting the field. On error the field is left
+// unchanged.
 func setField(section reflect.Value, f field, value any) error {
 	newValue, err := convert(value, f.typ)
 	if err != nil {
@@ -234,6 +237,8 @@ func convert(value any, t reflect.Type) (reflect.Value, error) {
 	return reflect.Value{}, fmt.Errorf("unsupported type %T", value)
 }
 
+// parseString parses s as a value of type t. It supports strings, bools,
+// signed and unsigned integers, floats and time.Duration.
 func parseString(s string, t reflect.Type) (reflect.Value, error) {
 	v := reflect.New(t).Elem()
 	if t == durationType {
@@ -280,6 +285,9 @@ func applyDefaults(ptr any) error {
 	return applyDefaultsTo("", structValue(ptr))
 }
 
+// applyDefaultsTo sets every field in section that has a default tag,
+// recursing into nested sections. prefix is the section's dotted key, used in
+// error messages.
 func applyDefaultsTo(prefix string, section reflect.Value) error {
 	for _, f := range fieldsOf(section.Type()) {
 		key := joinKey(prefix, f.key)