Re-add global env variable substitution (#227)

Co-authored-by: Stanislau Arsoba <sarsoba@klika-tech.com>

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Setup go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go }}
       - run: go test

cmd/godotenv/cmd.go

@@ -4,7 +4,6 @@ import (
 	"flag"
 	"fmt"
 	"log"
-
 	"strings"
 
 	"github.com/joho/godotenv"

fixtures/substitutions.env

@@ -3,3 +3,4 @@ OPTION_B=${OPTION_A}
 OPTION_C=$OPTION_B
 OPTION_D=${OPTION_A}${OPTION_B}
 OPTION_E=${OPTION_NOT_DEFINED}
+OPTION_F=${GLOBAL_OPTION}

godotenv_test.go

@@ -207,15 +207,21 @@ func TestLoadQuotedEnv(t *testing.T) {
 
 func TestSubstitutions(t *testing.T) {
 	envFileName := "fixtures/substitutions.env"
+
+	presets := map[string]string{
+		"GLOBAL_OPTION": "global",
+	}
+
 	expectedValues := map[string]string{
 		"OPTION_A": "1",
 		"OPTION_B": "1",
 		"OPTION_C": "1",
 		"OPTION_D": "11",
 		"OPTION_E": "",
+		"OPTION_F": "global",
 	}
 
-	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
+	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, presets)
 }
 
 func TestExpanding(t *testing.T) {
@@ -573,3 +579,64 @@ func TestTrailingNewlines(t *testing.T) {
 		})
 	}
 }
+
+func TestWhitespace(t *testing.T) {
+	cases := map[string]struct {
+		input string
+		key   string
+		value string
+	}{
+		"Leading whitespace": {
+			input: " A=a\n",
+			key: "A",
+			value: "a",
+		},
+		"Leading tab": {
+			input: "\tA=a\n",
+			key: "A",
+			value: "a",
+		},
+		"Leading mixed whitespace": {
+			input: " \t \t\n\t \t A=a\n",
+			key: "A",
+			value: "a",
+		},
+		"Leading whitespace before export": {
+			input: " \t\t export    A=a\n",
+			key: "A",
+			value: "a",
+		},
+		"Trailing whitespace": {
+			input: "A=a \t \t\n",
+			key: "A",
+			value: "a",
+		},
+		"Trailing whitespace with export": {
+			input: "export A=a\t \t \n",
+			key: "A",
+			value: "a",
+		},
+		"No EOL": {
+			input: "A=a",
+			key: "A",
+			value: "a",
+		},
+		"Trailing whitespace with no EOL": {
+			input: "A=a ",
+			key: "A",
+			value: "a",
+		},
+	}
+
+	for n, c := range cases {
+		t.Run(n, func(t *testing.T) {
+			result, err := Unmarshal(c.input)
+			if err != nil {
+				t.Errorf("Input: %q Unexpected error:\t%q", c.input, err)
+			}
+			if result[c.key] != c.value {
+				t.Errorf("Input %q Expected:\t %q/%q\nGot:\t %q", c.input, c.key, c.value, result)
+			}
+		})
+	}
+}

parser.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"os"
 	"regexp"
 	"strings"
 	"unicode"
@@ -264,6 +265,12 @@ func expandVariables(v string, m map[string]string) string {
 		if submatch[1] == "\\" || submatch[2] == "(" {
 			return submatch[0][1:]
 		} else if submatch[4] != "" {
+			if val, ok := m[submatch[4]]; ok {
+				return val
+			}
+			if val, ok := os.LookupEnv(submatch[4]); ok {
+				return val
+			}
 			return m[submatch[4]]
 		}
 		return s