added LoadFS from embed files

go.mod

@@ -1,3 +1,3 @@
 module github.com/joho/godotenv
 
-go 1.12
+go 1.16

godotenv.go

@@ -15,6 +15,7 @@ package godotenv
 
 import (
 	"bufio"
+	"embed"
 	"errors"
 	"fmt"
 	"io"
@@ -51,6 +52,50 @@ func Load(filenames ...string) (err error) {
 	return
 }
 
+func LoadFS(fsys embed.FS, filenames ...string) (err error) {
+	filenames = filenamesOrDefault(filenames)
+
+	for _, filename := range filenames {
+		err = loadFileFS(fsys, filename, false)
+		if err != nil {
+			return // return early on a spazout
+		}
+	}
+	return
+}
+
+func loadFileFS(fsys embed.FS, filename string, overload bool) error {
+	envMap, err := readFileFS(fsys, filename)
+	if err != nil {
+		return err
+	}
+
+	currentEnv := map[string]bool{}
+	rawEnv := os.Environ()
+	for _, rawEnvLine := range rawEnv {
+		key := strings.Split(rawEnvLine, "=")[0]
+		currentEnv[key] = true
+	}
+
+	for key, value := range envMap {
+		if !currentEnv[key] || overload {
+			os.Setenv(key, value)
+		}
+	}
+
+	return nil
+}
+
+func readFileFS(fsys embed.FS, filename string) (envMap map[string]string, err error) {
+	file, err := fsys.Open(filename)
+	if err != nil {
+		return
+	}
+	defer file.Close()
+
+	return Parse(file)
+}
+
 // Overload will read your env file(s) and load them into ENV for this process.
 //
 // Call this function as close as possible to the start of your program (ideally in main)
@@ -74,6 +119,18 @@ func Overload(filenames ...string) (err error) {
 	return
 }
 
+func OverloadFS(fsys embed.FS, filenames ...string) (err error) {
+	filenames = filenamesOrDefault(filenames)
+
+	for _, filename := range filenames {
+		err = loadFileFS(fsys, filename, true)
+		if err != nil {
+			return // return early on a spazout
+		}
+	}
+	return
+}
+
 // Read all env (with same file loading semantics as Load) but return values as
 // a map rather than automatically writing values into env
 func Read(filenames ...string) (envMap map[string]string, err error) {

godotenv_test.go

@@ -2,6 +2,7 @@ package godotenv
 
 import (
 	"bytes"
+	"embed"
 	"fmt"
 	"os"
 	"reflect"
@@ -11,6 +12,9 @@ import (
 
 var noopPresets = make(map[string]string)
 
+//go:embed fixtures/*
+var content embed.FS
+
 func parseAndCompare(t *testing.T, rawEnvLine string, expectedKey string, expectedValue string) {
 	key, value, _ := parseLine(rawEnvLine, noopPresets)
 	if key != expectedKey || value != expectedValue {
@@ -40,6 +44,28 @@ func loadEnvAndCompareValues(t *testing.T, loader func(files ...string) error, e
 	}
 }
 
+func loadFSEnvAndCompareValues(t *testing.T, loader func(fsys embed.FS, files ...string) error, fsys embed.FS, envFileName string, expectedValues map[string]string, presets map[string]string) {
+	// first up, clear the env
+	os.Clearenv()
+
+	for k, v := range presets {
+		os.Setenv(k, v)
+	}
+
+	err := loader(fsys, envFileName)
+	if err != nil {
+		t.Fatalf("Error loading %v", envFileName)
+	}
+
+	for k := range expectedValues {
+		envValue := os.Getenv(k)
+		v := expectedValues[k]
+		if envValue != v {
+			t.Errorf("Mismatch for key '%v': expected '%v' got '%v'", k, v, envValue)
+		}
+	}
+}
+
 func TestLoadWithNoArgsLoadsDotEnv(t *testing.T) {
 	err := Load()
 	pathError := err.(*os.PathError)
@@ -48,6 +74,14 @@ func TestLoadWithNoArgsLoadsDotEnv(t *testing.T) {
 	}
 }
 
+func TestLoadFSWithNoArgsLoadsDotEnv(t *testing.T) {
+	err := LoadFS(content)
+	pathError := err.(*os.PathError)
+	if pathError == nil || pathError.Op != "open" || pathError.Path != ".env" {
+		t.Errorf("Didn't try and open .env by default")
+	}
+}
+
 func TestOverloadWithNoArgsOverloadsDotEnv(t *testing.T) {
 	err := Overload()
 	pathError := err.(*os.PathError)
@@ -56,20 +90,42 @@ func TestOverloadWithNoArgsOverloadsDotEnv(t *testing.T) {
 	}
 }
 
+func TestOverloadFSWithNoArgsOverloadsDotEnv(t *testing.T) {
+	err := OverloadFS(content)
+	pathError := err.(*os.PathError)
+	if pathError == nil || pathError.Op != "open" || pathError.Path != ".env" {
+		t.Errorf("Didn't try and open .env by default")
+	}
+}
+
 func TestLoadFileNotFound(t *testing.T) {
 	err := Load("somefilethatwillneverexistever.env")
 	if err == nil {
 		t.Error("File wasn't found but Load didn't return an error")
 	}
 }
 
+func TestLoadFSFileNotFound(t *testing.T) {
+	err := LoadFS(content, "somefilethatwillneverexistever.env")
+	if err == nil {
+		t.Error("File wasn't found but LoadFS didn't return an error")
+	}
+}
+
 func TestOverloadFileNotFound(t *testing.T) {
 	err := Overload("somefilethatwillneverexistever.env")
 	if err == nil {
 		t.Error("File wasn't found but Overload didn't return an error")
 	}
 }
 
+func TestOverloadFSFileNotFound(t *testing.T) {
+	err := OverloadFS(content,"somefilethatwillneverexistever.env")
+	if err == nil {
+		t.Error("File wasn't found but Overload didn't return an error")
+	}
+}
+
 func TestReadPlainEnv(t *testing.T) {
 	envFileName := "fixtures/plain.env"
 	expectedValues := map[string]string{
@@ -131,6 +187,22 @@ func TestLoadDoesNotOverride(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, presets)
 }
 
+func TestLoadFSDoesNotOverride(t *testing.T) {
+	envFileName := "fixtures/plain.env"
+
+	// ensure NO overload
+	presets := map[string]string{
+		"OPTION_A": "do_not_override",
+		"OPTION_B": "",
+	}
+
+	expectedValues := map[string]string{
+		"OPTION_A": "do_not_override",
+		"OPTION_B": "",
+	}
+	loadFSEnvAndCompareValues(t, LoadFS, content, envFileName, expectedValues, presets)
+}
+
 func TestOveroadDoesOverride(t *testing.T) {
 	envFileName := "fixtures/plain.env"
 
@@ -145,6 +217,20 @@ func TestOveroadDoesOverride(t *testing.T) {
 	loadEnvAndCompareValues(t, Overload, envFileName, expectedValues, presets)
 }
 
+func TestOveroadFSDoesOverride(t *testing.T) {
+	envFileName := "fixtures/plain.env"
+
+	// ensure NO overload
+	presets := map[string]string{
+		"OPTION_A": "do_not_override",
+	}
+
+	expectedValues := map[string]string{
+		"OPTION_A": "1",
+	}
+	loadFSEnvAndCompareValues(t, OverloadFS, content, envFileName, expectedValues, presets)
+}
+
 func TestLoadPlainEnv(t *testing.T) {
 	envFileName := "fixtures/plain.env"
 	expectedValues := map[string]string{
@@ -158,6 +244,19 @@ func TestLoadPlainEnv(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestLoadFSPlainEnv(t *testing.T) {
+	envFileName := "fixtures/plain.env"
+	expectedValues := map[string]string{
+		"OPTION_A": "1",
+		"OPTION_B": "2",
+		"OPTION_C": "3",
+		"OPTION_D": "4",
+		"OPTION_E": "5",
+	}
+
+	loadFSEnvAndCompareValues(t, LoadFS, content, envFileName, expectedValues, noopPresets)
+}
+
 func TestLoadExportedEnv(t *testing.T) {
 	envFileName := "fixtures/exported.env"
 	expectedValues := map[string]string{
@@ -168,6 +267,16 @@ func TestLoadExportedEnv(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestLoadFSExportedEnv(t *testing.T) {
+	envFileName := "fixtures/exported.env"
+	expectedValues := map[string]string{
+		"OPTION_A": "2",
+		"OPTION_B": "\\n",
+	}
+
+	loadFSEnvAndCompareValues(t, LoadFS, content, envFileName, expectedValues, noopPresets)
+}
+
 func TestLoadEqualsEnv(t *testing.T) {
 	envFileName := "fixtures/equals.env"
 	expectedValues := map[string]string{
@@ -177,6 +286,15 @@ func TestLoadEqualsEnv(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestLoadFSEqualsEnv(t *testing.T) {
+	envFileName := "fixtures/equals.env"
+	expectedValues := map[string]string{
+		"OPTION_A": "postgres://localhost:5432/database?sslmode=disable",
+	}
+
+	loadFSEnvAndCompareValues(t, LoadFS, content, envFileName, expectedValues, noopPresets)
+}
+
 func TestLoadQuotedEnv(t *testing.T) {
 	envFileName := "fixtures/quoted.env"
 	expectedValues := map[string]string{
@@ -194,6 +312,23 @@ func TestLoadQuotedEnv(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestLoadFSQuotedEnv(t *testing.T) {
+	envFileName := "fixtures/quoted.env"
+	expectedValues := map[string]string{
+		"OPTION_A": "1",
+		"OPTION_B": "2",
+		"OPTION_C": "",
+		"OPTION_D": "\\n",
+		"OPTION_E": "1",
+		"OPTION_F": "2",
+		"OPTION_G": "",
+		"OPTION_H": "\n",
+		"OPTION_I": "echo 'asd'",
+	}
+
+	loadFSEnvAndCompareValues(t, LoadFS, content, envFileName, expectedValues, noopPresets)
+}
+
 func TestSubstitutions(t *testing.T) {
 	envFileName := "fixtures/substitutions.env"
 	expectedValues := map[string]string{
@@ -207,6 +342,19 @@ func TestSubstitutions(t *testing.T) {
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestFSSubstitutions(t *testing.T) {
+	envFileName := "fixtures/substitutions.env"
+	expectedValues := map[string]string{
+		"OPTION_A": "1",
+		"OPTION_B": "1",
+		"OPTION_C": "1",
+		"OPTION_D": "11",
+		"OPTION_E": "",
+	}
+
+	loadFSEnvAndCompareValues(t, LoadFS, content, envFileName, expectedValues, noopPresets)
+}
+
 func TestExpanding(t *testing.T) {
 	tests := []struct {
 		name     string
@@ -281,6 +429,16 @@ func TestActualEnvVarsAreLeftAlone(t *testing.T) {
 	}
 }
 
+func TestFSActualEnvVarsAreLeftAlone(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("OPTION_A", "actualenv")
+	_ = LoadFS(content, "fixtures/plain.env")
+
+	if os.Getenv("OPTION_A") != "actualenv" {
+		t.Error("An ENV var set earlier was overwritten")
+	}
+}
+
 func TestParsing(t *testing.T) {
 	// unquoted values
 	parseAndCompare(t, "FOO=bar", "FOO", "bar")