return error on invalid Feed() input, add tests to pass coverage, go …

…mod tidy

go.mod

@@ -4,7 +4,7 @@ go 1.11
 
 require (
 	github.com/BurntSushi/toml v0.4.1
-	github.com/golobby/cast v1.3.0 // indirect
+	github.com/golobby/cast v1.3.0
 	github.com/golobby/dotenv v1.3.1
 	github.com/golobby/env/v2 v2.2.0
 	github.com/stretchr/testify v1.7.0

pkg/feeder/default.go

@@ -2,9 +2,10 @@ package feeder
 
 import (
 	"fmt"
-	"github.com/golobby/cast"
 	"reflect"
 	"unsafe"
+
+	"github.com/golobby/cast"
 )
 
 // Default is a feeder.
@@ -23,7 +24,7 @@ func (f Default) Feed(structure interface{}) error {
 		}
 	}
 
-	return nil
+	return fmt.Errorf("default: input is not a struct pointer: %v --> %T", structure, structure)
 }
 
 // fillStruct sets a reflected struct fields with the default value.

pkg/feeder/default_test.go

@@ -1,9 +1,10 @@
 package feeder_test
 
 import (
+	"testing"
+
 	"github.com/golobby/config/v3/pkg/feeder"
 	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 func TestDefault_Feed(t *testing.T) {
@@ -37,3 +38,29 @@ func TestDefault_Feed_With_Invalid_Struct_It_Should_Fail(t *testing.T) {
 	err := f.Feed(&c)
 	assert.Error(t, err)
 }
+
+func TestDefault_Feed_With_Invalid_Inner_Struct_It_Should_Fail(t *testing.T) {
+	type HttpConf struct {
+		RequestTimeoutMs float64 `default:"string"`
+	}
+	type App struct {
+		Name string `env:"APP_NAME" default:"string"`
+		Http *HttpConf
+	}
+	c := App{
+		Http: &HttpConf{},
+	}
+
+	f := feeder.Default{}
+	err := f.Feed(&c)
+	assert.Error(t, err)
+
+}
+
+func TestDefault_Feed_With_Non_Struct_Type_Should_Fail(t *testing.T) {
+	c := 42
+	f := feeder.Default{}
+
+	err := f.Feed(c)
+	assert.Error(t, err)
+}