Changed yaml loader API

examples/xload/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"os"
 	"time"
 
 	"github.com/gojekfarm/xtools/xload"
@@ -23,16 +24,24 @@ func main() {
 	// from yaml, and then from environment variables
 	cfg := newAppConfig()
 
-	yamlLoader, _ := yaml.NewFileLoader("application.yaml", "_")
+	f, err := os.Open("application.yaml")
+	if err != nil {
+		panic(err)
+	}
+
+	yamlLoader, err := yaml.NewLoader(f, "_")
+	if err != nil {
+		panic(err)
+	}
 
-	err := xload.Load(
+	err = xload.Load(
 		ctx,
 		cfg,
 		xload.FieldTagName("env"),
 		xload.WithLoader(
 			xload.SerialLoader(
 				yamlLoader,
-				xload.OSLoader(),
+				xload.OSLoader(), // OSLoader values take precedence over yaml
 			),
 		),
 	)
@@ -50,7 +59,12 @@ func main() {
 	// middleware.
 	rcfg := newRequestConfig()
 
-	reqYamlLoader, err := yaml.NewFileLoader("request.default.yaml", "_")
+	rf, err := os.Open("request.default.yaml")
+	if err != nil {
+		panic(err)
+	}
+
+	reqYamlLoader, err := yaml.NewLoader(rf, "_")
 	if err != nil {
 		panic(err)
 	}
@@ -62,7 +76,7 @@ func main() {
 		xload.WithLoader(
 			xload.SerialLoader(
 				reqYamlLoader,
-				businessConfigLoader(),
+				businessConfigLoader(), // businessConfigLoader values take precedence over yaml
 			),
 		),
 	)
@@ -71,6 +85,9 @@ func main() {
 	}
 
 	prettyPrint(rcfg)
+
+	_ = rf.Close()
+	_ = f.Close()
 }
 
 func prettyPrint(v interface{}) {

xload/load_test.go

@@ -25,7 +25,7 @@ func TestLoadEnv(t *testing.T) {
 		Host string `config:"XLOAD_HOST"`
 	}{}
 
-	os.Setenv("XLOAD_HOST", "localhost")
+	_ = os.Setenv("XLOAD_HOST", "localhost")
 
 	err := LoadEnv(context.Background(), cfg)
 	require.NoError(t, err)

xload/providers/yaml/go.mod

@@ -9,4 +9,12 @@ require (
 	gopkg.in/yaml.v3 v3.0.1
 )
 
-require github.com/spf13/cast v1.5.1
+require (
+	github.com/spf13/cast v1.5.1
+	github.com/stretchr/testify v1.8.4
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+)

xload/providers/yaml/go.sum

@@ -1,14 +1,17 @@
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/frankban/quicktest v1.14.4 h1:g2rn0vABPOOXmZUj+vbmUp0lPoXEMuhTpIluN0XL9UY=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/gotidy/ptr v1.4.0 h1:7++suUs+HNHMnyz6/AW3SE+4EnBhupPSQTSI7QNijVc=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
 github.com/spf13/cast v1.5.1 h1:R+kOtfhWQE6TVQzY+4D7wJLBgkdVasCEFxSUBYBYIlA=
 github.com/spf13/cast v1.5.1/go.mod h1:b9PdjNptOpzXr7Rq1q9gJML/2cdGQAo69NKzQ10KN48=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

xload/providers/yaml/yaml.go

@@ -2,29 +2,24 @@
 package yaml
 
 import (
-	"os"
+	"io"
 
 	"github.com/spf13/cast"
 	"gopkg.in/yaml.v3"
 
 	"github.com/gojekfarm/xtools/xload"
 )
 
-// NewFileLoader reads YAML file and returns a xload.Loader
-func NewFileLoader(filename string, delim string) (xload.Loader, error) {
-	b, err := os.ReadFile(filename)
+// NewLoader reads YAML from the given io.Reader and returns a xload.Loader
+func NewLoader(r io.Reader, delim string) (xload.Loader, error) {
+	b, err := io.ReadAll(r)
 	if err != nil {
 		return nil, err
 	}
 
-	return NewBytesLoader(b, delim)
-}
-
-// NewBytesLoader reads YAML bytes and returns a xload.Loader
-func NewBytesLoader(b []byte, delim string) (xload.Loader, error) {
 	var out map[string]interface{}
 
-	err := yaml.Unmarshal(b, &out)
+	err = yaml.Unmarshal(b, &out)
 	if err != nil {
 		return nil, err
 	}

xload/providers/yaml/yaml_test.go

@@ -0,0 +1,69 @@
+// Package yaml provides a YAML loader for xload.
+package yaml
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewLoader(t *testing.T) {
+	yaml := `
+NAME: "Bombay Bob"
+AGE: 30
+ADDRESS:
+  STREET: "123 Main St"
+  CITY: "Bombay"
+`
+
+	b := bytes.NewBufferString(yaml)
+
+	l, err := NewLoader(b, "_")
+	assert.NoError(t, err)
+	assert.NotNil(t, l)
+
+	ctx := context.Background()
+
+	name, err := l.Load(ctx, "NAME")
+	assert.NoError(t, err)
+	assert.Equal(t, "Bombay Bob", name)
+
+	street, err := l.Load(ctx, "ADDRESS_STREET")
+	assert.NoError(t, err)
+	assert.Equal(t, "123 Main St", street)
+
+	phone, err := l.Load(ctx, "PHONE")
+	assert.NoError(t, err)
+	assert.Equal(t, "", phone)
+}
+
+func TestNewLoader_InvalidYAML(t *testing.T) {
+	yaml := `a
+b`
+
+	b := bytes.NewBufferString(yaml)
+
+	l, err := NewLoader(b, "_")
+	assert.Error(t, err)
+	assert.Nil(t, l)
+}
+
+type errReader struct{}
+
+func (e errReader) Read(p []byte) (n int, err error) {
+	return 0, errors.New("simulated error")
+}
+
+func TestNewLoader_ReaderError(t *testing.T) {
+	b := errReader{}
+
+	_, _ = io.ReadAll(b)
+
+	l, err := NewLoader(b, "_")
+	assert.Error(t, err)
+	assert.Nil(t, l)
+}