Adds a LoadFiles function

CHANGELOG.md

@@ -0,0 +1,11 @@
+# Changelog
+
+## Unreleased
+
+- Added License
+- Changed the go version to 1.17
+- Added a Loadfiles function to load at once several config files
+
+## v0.1.0 (2020-03-17)
+- Initial varsion
+

config.go

@@ -4,6 +4,7 @@ package conf
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -16,6 +17,23 @@ func LoadFile(path string, data interface{}) error {
 	return read(path, data)
 }
 
+// LoadFiles tries to load all the given paths in the given order.
+//
+// If a path does not exist, it is ignored.
+//
+// It returns an error only if the content of a file is invalid, i.e. it
+// cannot be unmarshaled by json.
+func LoadFiles(data interface{}, paths ...string) error {
+	for _, p := range paths {
+		err := read(p, data)
+		if err != nil && !errors.Is(err, os.ErrNotExist) {
+			return fmt.Errorf("cannot load %q: %w", p, err)
+		}
+	}
+
+	return nil
+}
+
 // SaveFile writes the given data serialized in JSON in the given path
 func SaveFile(path string, data interface{}) error {
 	return write(path, data)

config_test.go

@@ -3,6 +3,7 @@ package conf
 import (
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"testing"
 
 	. "github.com/smartystreets/goconvey/convey"
@@ -94,6 +95,115 @@ func TestLoadFile(t *testing.T) {
 	})
 }
 
+func TestLoadFiles(t *testing.T) {
+	Convey("Given a config struct", t, func() {
+		c := &testconf{}
+		tmpDir := t.TempDir()
+
+		Convey("Given two existing files setting different options", func() {
+			content1 := []byte(`{"String": "foo"}`)
+			content2 := []byte(`{"Int": 42}`)
+			paths := []string{
+				filepath.Join(tmpDir, "file1.json"),
+				filepath.Join(tmpDir, "file2.json"),
+			}
+
+			err := ioutil.WriteFile(paths[0], content1, 0o600)
+			So(err, ShouldBeNil)
+			err = ioutil.WriteFile(paths[1], content2, 0o600)
+			So(err, ShouldBeNil)
+
+			Convey("When LoadFiles is called", func() {
+				err := LoadFiles(&c, paths...)
+
+				Convey("Then there is no error", func() {
+					So(err, ShouldBeNil)
+
+					Convey("And the options from both files have been set", func() {
+						So(c.String, ShouldEqual, "foo")
+						So(c.Int, ShouldEqual, 42)
+					})
+				})
+			})
+		})
+
+		Convey("Given two existing files setting the same option", func() {
+			content1 := []byte(`{"String": "foo"}`)
+			content2 := []byte(`{"String": "bar"}`)
+			paths := []string{
+				filepath.Join(tmpDir, "file1.json"),
+				filepath.Join(tmpDir, "file2.json"),
+			}
+
+			err := ioutil.WriteFile(paths[0], content1, 0o600)
+			So(err, ShouldBeNil)
+			err = ioutil.WriteFile(paths[1], content2, 0o600)
+			So(err, ShouldBeNil)
+
+			Convey("When LoadFiles is called", func() {
+				err := LoadFiles(&c, paths...)
+
+				Convey("Then there is no error", func() {
+					So(err, ShouldBeNil)
+
+					Convey("And the last file overwrote the first", func() {
+						So(c.String, ShouldEqual, "bar")
+					})
+				})
+			})
+		})
+
+		Convey("Given one non-existing and one existing files", func() {
+			content2 := []byte(`{"String": "bar"}`)
+			paths := []string{
+				"does-not-exist.json",
+				filepath.Join(tmpDir, "file2.json"),
+			}
+
+			err := ioutil.WriteFile(paths[1], content2, 0o600)
+			So(err, ShouldBeNil)
+
+			Convey("When LoadFiles is called", func() {
+				err := LoadFiles(&c, paths...)
+
+				Convey("Then there is no error", func() {
+					So(err, ShouldBeNil)
+
+					Convey("And the options from the last file have been set", func() {
+						So(c.String, ShouldEqual, "bar")
+					})
+				})
+			})
+		})
+
+		Convey("Given one invalid and one valid files", func() {
+			content1 := []byte(`{"`)
+			content2 := []byte(`{"String": "bar"}`)
+			paths := []string{
+				filepath.Join(tmpDir, "file1.json"),
+				filepath.Join(tmpDir, "file2.json"),
+			}
+
+			err := ioutil.WriteFile(paths[0], content1, 0o600)
+			So(err, ShouldBeNil)
+			err = ioutil.WriteFile(paths[1], content2, 0o600)
+			So(err, ShouldBeNil)
+
+			Convey("When LoadFiles is called", func() {
+				err := LoadFiles(&c, paths...)
+
+				Convey("Then an error is returned", func() {
+					So(err, ShouldBeError)
+
+					Convey("And the last file has not been read", func() {
+						So(c.String, ShouldNotEqual, "bar")
+					})
+				})
+			})
+		})
+	})
+}
+
 func TestSaveFile(t *testing.T) {
 	Convey("Given a config struct", t, func() {
 		c := testconf{

go.mod

@@ -1,3 +1,11 @@
 module code.bcarlin.xyz/go/conf
 
-go 1.14
+go 1.17
+
+require github.com/smartystreets/goconvey v1.7.2
+
+require (
+	github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 // indirect
+	github.com/jtolds/gls v4.20.0+incompatible // indirect
+	github.com/smartystreets/assertions v1.2.0 // indirect
+)

go.sum

@@ -0,0 +1,13 @@
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 h1:EGx4pi6eqNxGaHF6qqu48+N2wcFQ5qg5FXgOdqsJ5d8=
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
+github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7C0MuV77Wo=
+github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
+github.com/smartystreets/assertions v1.2.0 h1:42S6lae5dvLc7BrLu/0ugRtcFVjoJNMC/N3yZFZkDFs=
+github.com/smartystreets/assertions v1.2.0/go.mod h1:tcbTF8ujkAEcZ8TElKY+i30BzYlVhC/LOxJk7iOWnoo=
+github.com/smartystreets/goconvey v1.7.2 h1:9RBaZCeXEQ3UselpuwUQHltGVXvdwm6cv1hgR6gDIPg=
+github.com/smartystreets/goconvey v1.7.2/go.mod h1:Vw0tHAZW6lzCRk3xgdin6fKYcG+G3Pg9vgXWeJpQFMM=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=