Change check of existing env to respect empty (but set) vars.

allow usage of empty var on .env

fixtures/plain.env

@@ -3,3 +3,5 @@ OPTION_B=2
 OPTION_C= 3
 OPTION_D =4
 OPTION_E = 5
+OPTION_F = 
+OPTION_G=

godotenv.go

@@ -119,8 +119,15 @@ func loadFile(filename string, overload bool) error {
 		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 os.Getenv(key) == "" || overload {
+		if !currentEnv[key] || overload {
 			os.Setenv(key, value)
 		}
 	}
@@ -212,18 +219,23 @@ func parseLine(line string) (key string, value string, err error) {
 
 	// Parse the value
 	value = splitString[1]
+
 	// trim
 	value = strings.Trim(value, " ")
 
 	// check if we've got quoted values
-	if strings.Count(value, "\"") == 2 || strings.Count(value, "'") == 2 {
-		// pull the quotes off the edges
-		value = strings.Trim(value, "\"'")
+	if value != "" {
+		first := string(value[0:1])
+		last := string(value[len(value)-1:])
+		if first == last && strings.ContainsAny(first, `"'`) {
+			// pull the quotes off the edges
+			value = strings.Trim(value, `"'`)
 
-		// expand quotes
-		value = strings.Replace(value, "\\\"", "\"", -1)
-		// expand newlines
-		value = strings.Replace(value, "\\n", "\n", -1)
+			// expand quotes
+			value = strings.Replace(value, `\"`, `"`, -1)
+			// expand newlines
+			value = strings.Replace(value, `\n`, "\n", -1)
+		}
 	}
 
 	return

godotenv_test.go

@@ -74,6 +74,8 @@ func TestReadPlainEnv(t *testing.T) {
 		"OPTION_C": "3",
 		"OPTION_D": "4",
 		"OPTION_E": "5",
+		"OPTION_F": "",
+		"OPTION_G": "",
 	}
 
 	envMap, err := Read(envFileName)
@@ -98,10 +100,12 @@ func TestLoadDoesNotOverride(t *testing.T) {
 	// 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": "",
 	}
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, presets)
 }
@@ -187,24 +191,24 @@ func TestParsing(t *testing.T) {
 	parseAndCompare(t, "FOO= bar", "FOO", "bar")
 
 	// parses double quoted values
-	parseAndCompare(t, "FOO=\"bar\"", "FOO", "bar")
+	parseAndCompare(t, `FOO="bar"`, "FOO", "bar")
 
 	// parses single quoted values
 	parseAndCompare(t, "FOO='bar'", "FOO", "bar")
 
 	// parses escaped double quotes
-	parseAndCompare(t, "FOO=escaped\\\"bar\"", "FOO", "escaped\"bar")
+	parseAndCompare(t, `FOO="escaped\"bar"`, "FOO", `escaped"bar`)
 
 	// parses yaml style options
 	parseAndCompare(t, "OPTION_A: 1", "OPTION_A", "1")
 
 	// parses export keyword
 	parseAndCompare(t, "export OPTION_A=2", "OPTION_A", "2")
-	parseAndCompare(t, "export OPTION_B='\\n'", "OPTION_B", "\n")
+	parseAndCompare(t, `export OPTION_B='\n'`, "OPTION_B", "\n")
 
 	// it 'expands newlines in quoted strings' do
 	// expect(env('FOO="bar\nbaz"')).to eql('FOO' => "bar\nbaz")
-	parseAndCompare(t, "FOO=\"bar\\nbaz\"", "FOO", "bar\nbaz")
+	parseAndCompare(t, `FOO="bar\nbaz"`, "FOO", "bar\nbaz")
 
 	// it 'parses varibales with "." in the name' do
 	// expect(env('FOO.BAR=foobar')).to eql('FOO.BAR' => 'foobar')
@@ -224,14 +228,14 @@ func TestParsing(t *testing.T) {
 
 	// it 'allows # in quoted value' do
 	// expect(env('foo="bar#baz" # comment')).to eql('foo' => 'bar#baz')
-	parseAndCompare(t, "FOO=\"bar#baz\" # comment", "FOO", "bar#baz")
+	parseAndCompare(t, `FOO="bar#baz" # comment`, "FOO", "bar#baz")
 	parseAndCompare(t, "FOO='bar#baz' # comment", "FOO", "bar#baz")
-	parseAndCompare(t, "FOO=\"bar#baz#bang\" # comment", "FOO", "bar#baz#bang")
+	parseAndCompare(t, `FOO="bar#baz#bang" # comment`, "FOO", "bar#baz#bang")
 
 	// it 'parses # in quoted values' do
 	// expect(env('foo="ba#r"')).to eql('foo' => 'ba#r')
 	// expect(env("foo='ba#r'")).to eql('foo' => 'ba#r')
-	parseAndCompare(t, "FOO=\"ba#r\"", "FOO", "ba#r")
+	parseAndCompare(t, `FOO="ba#r"`, "FOO", "ba#r")
 	parseAndCompare(t, "FOO='ba#r'", "FOO", "ba#r")
 
 	// it 'throws an error if line format is incorrect' do
@@ -265,7 +269,7 @@ func TestLinesToIgnore(t *testing.T) {
 	}
 
 	// make sure we're not getting false positives
-	if isIgnoredLine("export OPTION_B='\\n'") {
+	if isIgnoredLine(`export OPTION_B='\n'`) {
 		t.Error("ignoring a perfectly valid line to parse")
 	}
 }