Add punctuation to please godoc

Fixes issue reported over at https://github.com/golang/go/issues/55888

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: /
+    schedule:
+      interval: "daily"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/workflows/ci.yml

@@ -0,0 +1,20 @@
+name: CI
+
+on: [push]
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        go: [ '1.18', '1.17', '1.16', '1.15' ]
+        os: [ ubuntu-latest, macOS-latest, windows-latest ]
+    name: ${{ matrix.os }} Go ${{ matrix.go }} Tests
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup go
+        uses: actions/setup-go@v3
+        with:
+          go-version: ${{ matrix.go }}
+      - run: go test

.github/workflows/codeql-analysis.yml

@@ -0,0 +1,72 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ "main" ]
+  schedule:
+    - cron: '31 4 * * 2'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'go' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
+        # Learn more about CodeQL language support at https://aka.ms/codeql-docs/language-support
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v2
+      with:
+        languages: ${{ matrix.language }}
+        # If you wish to specify custom queries, you can do so here or in a config file.
+        # By default, queries listed here will override any specified in a config file.
+        # Prefix the list here with "+" to use these queries and those in the config file.
+        
+        # Details on CodeQL's query packs refer to : https://docs.github.com/en/code-security/code-scanning/automatically-scanning-your-code-for-vulnerabilities-and-errors/configuring-code-scanning#using-queries-in-ql-packs
+        # queries: security-extended,security-and-quality
+
+        
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v2
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 See https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idstepsrun
+
+    #   If the Autobuild fails above, remove it and uncomment the following three lines. 
+    #   modify them (or add more) to build your code if your project, please refer to the EXAMPLE below for guidance.
+
+    # - run: |
+    #   echo "Run, Build Application using script"
+    #   ./location_of_script_within_repo/buildscript.sh
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v2

.github/workflows/release.yml

@@ -0,0 +1,31 @@
+on:
+  push:
+    tags:
+    - 'v*' # Push events to matching v*, i.e. v1.0, v20.15.10
+
+name: Upload Release Assets
+
+jobs:
+  build:
+    name: Upload Release Assets
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+      - name: Generate build files
+        uses: thatisuday/go-cross-build@v1.0.2
+        with:
+            platforms: 'linux/amd64, linux/ppc64le, darwin/amd64, darwin/arm64, windows/amd64'
+            package: 'cmd/godotenv'
+            name: 'godotenv'
+            compress: 'true'
+            dest: 'dist'
+      - name: Publish Binaries
+        uses: svenstaro/upload-release-action@v2
+        with:
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          release_name: Release ${{ github.ref }}
+          tag: ${{ github.ref }}
+          file: dist/*
+          file_glob: true
+          overwrite: true

.travis.yml

@@ -1,8 +0,0 @@
-language: go
-
-go:
-  - 1.8
-
-os:
-  - linux
-  - osx

README.md

@@ -1,6 +1,6 @@
-# GoDotEnv [![Build Status](https://travis-ci.org/joho/godotenv.svg?branch=master)](https://travis-ci.org/joho/godotenv) [![Build status](https://ci.appveyor.com/api/projects/status/9v40vnfvvgde64u4?svg=true)](https://ci.appveyor.com/project/joho/godotenv)
+# GoDotEnv ![CI](https://github.com/joho/godotenv/workflows/CI/badge.svg) [![Go Report Card](https://goreportcard.com/badge/github.com/joho/godotenv)](https://goreportcard.com/report/github.com/joho/godotenv)
 
-A Go (golang) port of the Ruby dotenv project (which loads env vars from a .env file)
+A Go (golang) port of the Ruby [dotenv](https://github.com/bkeepers/dotenv) project (which loads env vars from a .env file).
 
 From the original Library:
 
@@ -8,9 +8,9 @@ From the original Library:
 >
 > But it is not always practical to set environment variables on development machines or continuous integration servers where multiple projects are run. Dotenv load variables from a .env file into ENV when the environment is bootstrapped.
 
-It can be used as a library (for loading in env for your own daemons etc) or as a bin command.
+It can be used as a library (for loading in env for your own daemons etc.) or as a bin command.
 
-There is test coverage and CI for both linuxish and windows environments, but I make no guarantees about the bin version working on windows.
+There is test coverage and CI for both linuxish and Windows environments, but I make no guarantees about the bin version working on Windows.
 
 ## Installation
 
@@ -21,6 +21,13 @@ go get github.com/joho/godotenv
 ```
 
 or if you want to use it as a bin command
+
+go >= 1.17
+```shell
+go install github.com/joho/godotenv/cmd/godotenv@latest
+```
+
+go < 1.17
 ```shell
 go get github.com/joho/godotenv/cmd/godotenv
 ```
@@ -40,9 +47,10 @@ Then in your Go app you can do something like
 package main
 
 import (
-    "github.com/joho/godotenv"
     "log"
     "os"
+
+    "github.com/joho/godotenv"
 )
 
 func main() {
@@ -96,6 +104,45 @@ myEnv, err := godotenv.Read()
 s3Bucket := myEnv["S3_BUCKET"]
 ```
 
+... or from an `io.Reader` instead of a local file
+
+```go
+reader := getRemoteFile()
+myEnv, err := godotenv.Parse(reader)
+```
+
+... or from a `string` if you so desire
+
+```go
+content := getRemoteFileContent()
+myEnv, err := godotenv.Unmarshal(content)
+```
+
+### Precedence & Conventions
+
+Existing envs take precedence of envs that are loaded later.
+
+The [convention](https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use)
+for managing multiple environments (i.e. development, test, production)
+is to create an env named `{YOURAPP}_ENV` and load envs in this order:
+
+```go
+env := os.Getenv("FOO_ENV")
+if "" == env {
+  env = "development"
+}
+
+godotenv.Load(".env." + env + ".local")
+if "test" != env {
+  godotenv.Load(".env.local")
+}
+godotenv.Load(".env." + env)
+godotenv.Load() // The Original .env
+```
+
+If you need to, you can also use `godotenv.Overload()` to defy this convention
+and overwrite existing envs instead of only supplanting them. Use with caution.
+
 ### Command Mode
 
 Assuming you've installed the command as above and you've got `$GOPATH/bin` in your `$PATH`
@@ -106,11 +153,35 @@ godotenv -f /some/path/to/.env some_command with some args
 
 If you don't specify `-f` it will fall back on the default of loading `.env` in `PWD`
 
+### Writing Env Files
+
+Godotenv can also write a map representing the environment to a correctly-formatted and escaped file
+
+```go
+env, err := godotenv.Unmarshal("KEY=value")
+err := godotenv.Write(env, "./.env")
+```
+
+... or to a string
+
+```go
+env, err := godotenv.Unmarshal("KEY=value")
+content, err := godotenv.Marshal(env)
+```
+
 ## Contributing
 
-Contributions are most welcome! The parser itself is pretty stupidly naive and I wouldn't be surprised if it breaks with edge cases.
+Contributions are welcome, but with some caveats.
 
-*code changes without tests will not be accepted*
+This library has been declared feature complete (see [#182](https://github.com/joho/godotenv/issues/182) for background) and will not be accepting issues or pull requests adding new functionality or breaking the library API.
+
+Contributions would be gladly accepted that:
+
+* bring this library's parsing into closer compatibility with the mainline dotenv implementations, in particular [Ruby's dotenv](https://github.com/bkeepers/dotenv) and [Node.js' dotenv](https://github.com/motdotla/dotenv)
+* keep the library up to date with the go ecosystem (ie CI bumps, documentation changes, changes in the core libraries)
+* bug fixes for use cases that pertain to the library's purpose of easing development of codebases deployed into twelve factor environments
+
+*code changes without tests and references to peer dotenv implementations will not be accepted*
 
 1. Fork it
 2. Create your feature branch (`git checkout -b my-new-feature`)
@@ -118,10 +189,12 @@ Contributions are most welcome! The parser itself is pretty stupidly naive and I
 4. Push to the branch (`git push origin my-new-feature`)
 5. Create new Pull Request
 
-## CI
+## Releases
 
-Linux: [![wercker status](https://app.wercker.com/status/507594c2ec7e60f19403a568dfea0f78/m "wercker status")](https://app.wercker.com/project/bykey/507594c2ec7e60f19403a568dfea0f78) Windows: [![Build status](https://ci.appveyor.com/api/projects/status/9v40vnfvvgde64u4)](https://ci.appveyor.com/project/joho/godotenv)
+Releases should follow [Semver](http://semver.org/) though the first couple of releases are `v1` and `v1.1`.
+
+Use [annotated tags for all releases](https://github.com/joho/godotenv/issues/30). Example `git tag -a v1.2.1`
 
 ## Who?
 
-The original library [dotenv](https://github.com/bkeepers/dotenv) was written by [Brandon Keepers](http://opensoul.org/), and this port was done by [John Barton](http://whoisjohnbarton.com) based off the tests/fixtures in the original library.
+The original library [dotenv](https://github.com/bkeepers/dotenv) was written by [Brandon Keepers](http://opensoul.org/), and this port was done by [John Barton](https://johnbarton.co/) based off the tests/fixtures in the original library.

cmd/godotenv/cmd.go

@@ -19,7 +19,7 @@ func main() {
 	flag.Parse()
 
 	usage := `
-Run a process with a env setup from a .env file
+Run a process with an env setup from a .env file
 
 godotenv [-f ENV_FILE_PATHS] COMMAND_ARGS
 

fixtures/plain.env

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

fixtures/quoted.env

@@ -6,3 +6,4 @@ OPTION_E="1"
 OPTION_F="2"
 OPTION_G=""
 OPTION_H="\n"
+OPTION_I = "echo 'asd'"

fixtures/substitutions.env

@@ -0,0 +1,5 @@
+OPTION_A=1
+OPTION_B=${OPTION_A}
+OPTION_C=$OPTION_B
+OPTION_D=${OPTION_A}${OPTION_B}
+OPTION_E=${OPTION_NOT_DEFINED}

go.mod

@@ -0,0 +1,3 @@
+module github.com/joho/godotenv
+
+go 1.12

godotenv.go

@@ -1,6 +1,6 @@
 // Package godotenv is a go port of the ruby dotenv library (https://github.com/bkeepers/dotenv)
 //
-// Examples/readme can be found on the github page at https://github.com/joho/godotenv
+// Examples/readme can be found on the GitHub page at https://github.com/joho/godotenv
 //
 // The TL;DR is that you make a .env file that looks something like
 //
@@ -10,28 +10,35 @@
 //
 // 		godotenv.Load()
 //
-// and all the env vars declared in .env will be avaiable through os.Getenv("SOME_ENV_VAR")
+// and all the env vars declared in .env will be available through os.Getenv("SOME_ENV_VAR")
 package godotenv
 
 import (
 	"bufio"
 	"errors"
+	"fmt"
+	"io"
 	"os"
 	"os/exec"
+	"regexp"
+	"sort"
+	"strconv"
 	"strings"
 )
 
+const doubleQuoteSpecialChars = "\\\n\r\"!$`"
+
 // Load 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)
+// Call this function as close as possible to the start of your program (ideally in main).
 //
-// If you call Load without any args it will default to loading .env in the current path
+// If you call Load without any args it will default to loading .env in the current path.
 //
-// You can otherwise tell it which files to load (there can be more than one) like
+// You can otherwise tell it which files to load (there can be more than one) like:
 //
 //		godotenv.Load("fileone", "filetwo")
 //
-// It's important to note that it WILL NOT OVERRIDE an env variable that already exists - consider the .env file to set dev vars or sensible defaults
+// It's important to note that it WILL NOT OVERRIDE an env variable that already exists - consider the .env file to set dev vars or sensible defaults.
 func Load(filenames ...string) (err error) {
 	filenames = filenamesOrDefault(filenames)
 
@@ -46,15 +53,15 @@ func Load(filenames ...string) (err error) {
 
 // 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)
+// Call this function as close as possible to the start of your program (ideally in main).
 //
-// If you call Overload without any args it will default to loading .env in the current path
+// If you call Overload without any args it will default to loading .env in the current path.
 //
-// You can otherwise tell it which files to load (there can be more than one) like
+// You can otherwise tell it which files to load (there can be more than one) like:
 //
 //		godotenv.Overload("fileone", "filetwo")
 //
-// It's important to note this WILL OVERRIDE an env variable that already exists - consider the .env file to forcefilly set all vars.
+// It's important to note this WILL OVERRIDE an env variable that already exists - consider the .env file to forcefully set all vars.
 func Overload(filenames ...string) (err error) {
 	filenames = filenamesOrDefault(filenames)
 
@@ -89,10 +96,43 @@ func Read(filenames ...string) (envMap map[string]string, err error) {
 	return
 }
 
+// Parse reads an env file from io.Reader, returning a map of keys and values.
+func Parse(r io.Reader) (envMap map[string]string, err error) {
+	envMap = make(map[string]string)
+
+	var lines []string
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	if err = scanner.Err(); err != nil {
+		return
+	}
+
+	for _, fullLine := range lines {
+		if !isIgnoredLine(fullLine) {
+			var key, value string
+			key, value, err = parseLine(fullLine, envMap)
+
+			if err != nil {
+				return
+			}
+			envMap[key] = value
+		}
+	}
+	return
+}
+
+// Unmarshal reads an env file from a string, returning a map of keys and values.
+func Unmarshal(str string) (envMap map[string]string, err error) {
+	return Parse(strings.NewReader(str))
+}
+
 // Exec loads env vars from the specified filenames (empty map falls back to default)
 // then executes the cmd specified.
 //
-// Simply hooks up os.Stdin/err/out to the command and calls Run()
+// Simply hooks up os.Stdin/err/out to the command and calls Run().
 //
 // If you want more fine grained control over your command it's recommended
 // that you use `Load()` or `Read()` and the `os/exec` package yourself.
@@ -106,6 +146,40 @@ func Exec(filenames []string, cmd string, cmdArgs []string) error {
 	return command.Run()
 }
 
+// Write serializes the given environment and writes it to a file.
+func Write(envMap map[string]string, filename string) error {
+	content, err := Marshal(envMap)
+	if err != nil {
+		return err
+	}
+	file, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	_, err = file.WriteString(content + "\n")
+	if err != nil {
+		return err
+	}
+	file.Sync()
+	return err
+}
+
+// Marshal outputs the given environment as a dotenv-formatted environment file.
+// Each line is in the format: KEY="VALUE" where VALUE is backslash-escaped.
+func Marshal(envMap map[string]string) (string, error) {
+	lines := make([]string, 0, len(envMap))
+	for k, v := range envMap {
+		if d, err := strconv.Atoi(v); err == nil {
+			lines = append(lines, fmt.Sprintf(`%s=%d`, k, d))
+		} else {
+			lines = append(lines, fmt.Sprintf(`%s="%s"`, k, doubleQuoteEscape(v)))
+		}
+	}
+	sort.Strings(lines)
+	return strings.Join(lines, "\n"), nil
+}
+
 func filenamesOrDefault(filenames []string) []string {
 	if len(filenames) == 0 {
 		return []string{".env"}
@@ -119,8 +193,15 @@ 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)
 		}
 	}
@@ -135,33 +216,12 @@ func readFile(filename string) (envMap map[string]string, err error) {
 	}
 	defer file.Close()
 
-	envMap = make(map[string]string)
-
-	var lines []string
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		lines = append(lines, scanner.Text())
+	return Parse(file)
 }
 
-	if err = scanner.Err(); err != nil {
-		return
-	}
+var exportRegex = regexp.MustCompile(`^\s*(?:export\s+)?(.*?)\s*$`)
 
-	for _, fullLine := range lines {
-		if !isIgnoredLine(fullLine) {
-			var key, value string
-			key, value, err = parseLine(fullLine)
-
-			if err != nil {
-				return
-			}
-			envMap[key] = value
-		}
-	}
-	return
-}
-
-func parseLine(line string) (key string, value string, err error) {
+func parseLine(line string, envMap map[string]string) (key string, value string, err error) {
 	if len(line) == 0 {
 		err = errors.New("zero length string")
 		return
@@ -190,11 +250,11 @@ func parseLine(line string) (key string, value string, err error) {
 		line = strings.Join(segmentsToKeep, "#")
 	}
 
-	// now split key from value
+	firstEquals := strings.Index(line, "=")
+	firstColon := strings.Index(line, ":")
 	splitString := strings.SplitN(line, "=", 2)
-
-	if len(splitString) != 2 {
-		// try yaml mode!
+	if firstColon != -1 && (firstColon < firstEquals || firstEquals == -1) {
+		//this is a yaml-style line
 		splitString = strings.SplitN(line, ":", 2)
 	}
 
@@ -208,28 +268,96 @@ func parseLine(line string) (key string, value string, err error) {
 	if strings.HasPrefix(key, "export") {
 		key = strings.TrimPrefix(key, "export")
 	}
-	key = strings.Trim(key, " ")
+	key = strings.TrimSpace(key)
+
+	key = exportRegex.ReplaceAllString(splitString[0], "$1")
 
 	// 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, "\"'")
-
-		// expand quotes
-		value = strings.Replace(value, "\\\"", "\"", -1)
-		// expand newlines
-		value = strings.Replace(value, "\\n", "\n", -1)
-	}
-
+	value = parseValue(splitString[1], envMap)
 	return
 }
 
+var (
+	singleQuotesRegex  = regexp.MustCompile(`\A'(.*)'\z`)
+	doubleQuotesRegex  = regexp.MustCompile(`\A"(.*)"\z`)
+	escapeRegex        = regexp.MustCompile(`\\.`)
+	unescapeCharsRegex = regexp.MustCompile(`\\([^$])`)
+)
+
+func parseValue(value string, envMap map[string]string) string {
+
+	// trim
+	value = strings.Trim(value, " ")
+
+	// check if we've got quoted values or possible escapes
+	if len(value) > 1 {
+		singleQuotes := singleQuotesRegex.FindStringSubmatch(value)
+
+		doubleQuotes := doubleQuotesRegex.FindStringSubmatch(value)
+
+		if singleQuotes != nil || doubleQuotes != nil {
+			// pull the quotes off the edges
+			value = value[1 : len(value)-1]
+		}
+
+		if doubleQuotes != nil {
+			// expand newlines
+			value = escapeRegex.ReplaceAllStringFunc(value, func(match string) string {
+				c := strings.TrimPrefix(match, `\`)
+				switch c {
+				case "n":
+					return "\n"
+				case "r":
+					return "\r"
+				default:
+					return match
+				}
+			})
+			// unescape characters
+			value = unescapeCharsRegex.ReplaceAllString(value, "$1")
+		}
+
+		if singleQuotes == nil {
+			value = expandVariables(value, envMap)
+		}
+	}
+
+	return value
+}
+
+var expandVarRegex = regexp.MustCompile(`(\\)?(\$)(\()?\{?([A-Z0-9_]+)?\}?`)
+
+func expandVariables(v string, m map[string]string) string {
+	return expandVarRegex.ReplaceAllStringFunc(v, func(s string) string {
+		submatch := expandVarRegex.FindStringSubmatch(s)
+
+		if submatch == nil {
+			return s
+		}
+		if submatch[1] == "\\" || submatch[2] == "(" {
+			return submatch[0][1:]
+		} else if submatch[4] != "" {
+			return m[submatch[4]]
+		}
+		return s
+	})
+}
+
 func isIgnoredLine(line string) bool {
-	trimmedLine := strings.Trim(line, " \n\t")
+	trimmedLine := strings.TrimSpace(line)
 	return len(trimmedLine) == 0 || strings.HasPrefix(trimmedLine, "#")
 }
+
+func doubleQuoteEscape(line string) string {
+	for _, c := range doubleQuoteSpecialChars {
+		toReplace := "\\" + string(c)
+		if c == '\n' {
+			toReplace = `\n`
+		}
+		if c == '\r' {
+			toReplace = `\r`
+		}
+		line = strings.Replace(line, string(c), toReplace, -1)
+	}
+	return line
+}

godotenv_test.go

@@ -1,14 +1,18 @@
 package godotenv
 
 import (
+	"bytes"
+	"fmt"
 	"os"
+	"reflect"
+	"strings"
 	"testing"
 )
 
 var noopPresets = make(map[string]string)
 
 func parseAndCompare(t *testing.T, rawEnvLine string, expectedKey string, expectedValue string) {
-	key, value, _ := parseLine(rawEnvLine)
+	key, value, _ := parseLine(rawEnvLine, noopPresets)
 	if key != expectedKey || value != expectedValue {
 		t.Errorf("Expected '%v' to parse as '%v' => '%v', got '%v' => '%v' instead", rawEnvLine, expectedKey, expectedValue, key, value)
 	}
@@ -74,6 +78,8 @@ func TestReadPlainEnv(t *testing.T) {
 		"OPTION_C": "3",
 		"OPTION_D": "4",
 		"OPTION_E": "5",
+		"OPTION_F": "",
+		"OPTION_G": "",
 	}
 
 	envMap, err := Read(envFileName)
@@ -92,21 +98,40 @@ func TestReadPlainEnv(t *testing.T) {
 	}
 }
 
+func TestParse(t *testing.T) {
+	envMap, err := Parse(bytes.NewReader([]byte("ONE=1\nTWO='2'\nTHREE = \"3\"")))
+	expectedValues := map[string]string{
+		"ONE":   "1",
+		"TWO":   "2",
+		"THREE": "3",
+	}
+	if err != nil {
+		t.Fatalf("error parsing env: %v", err)
+	}
+	for key, value := range expectedValues {
+		if envMap[key] != value {
+			t.Errorf("expected %s to be %s, got %s", key, value, envMap[key])
+		}
+	}
+}
+
 func TestLoadDoesNotOverride(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": "",
 	}
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, presets)
 }
 
-func TestOveroadDoesOverride(t *testing.T) {
+func TestOverloadDoesOverride(t *testing.T) {
 	envFileName := "fixtures/plain.env"
 
 	// ensure NO overload
@@ -137,7 +162,7 @@ func TestLoadExportedEnv(t *testing.T) {
 	envFileName := "fixtures/exported.env"
 	expectedValues := map[string]string{
 		"OPTION_A": "2",
-		"OPTION_B": "\n",
+		"OPTION_B": "\\n",
 	}
 
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
@@ -158,16 +183,94 @@ func TestLoadQuotedEnv(t *testing.T) {
 		"OPTION_A": "1",
 		"OPTION_B": "2",
 		"OPTION_C": "",
-		"OPTION_D": "\n",
+		"OPTION_D": "\\n",
 		"OPTION_E": "1",
 		"OPTION_F": "2",
 		"OPTION_G": "",
 		"OPTION_H": "\n",
+		"OPTION_I": "echo 'asd'",
 	}
 
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
 
+func TestSubstitutions(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": "",
+	}
+
+	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
+}
+
+func TestExpanding(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected map[string]string
+	}{
+		{
+			"expands variables found in values",
+			"FOO=test\nBAR=$FOO",
+			map[string]string{"FOO": "test", "BAR": "test"},
+		},
+		{
+			"parses variables wrapped in brackets",
+			"FOO=test\nBAR=${FOO}bar",
+			map[string]string{"FOO": "test", "BAR": "testbar"},
+		},
+		{
+			"expands undefined variables to an empty string",
+			"BAR=$FOO",
+			map[string]string{"BAR": ""},
+		},
+		{
+			"expands variables in double quoted strings",
+			"FOO=test\nBAR=\"quote $FOO\"",
+			map[string]string{"FOO": "test", "BAR": "quote test"},
+		},
+		{
+			"does not expand variables in single quoted strings",
+			"BAR='quote $FOO'",
+			map[string]string{"BAR": "quote $FOO"},
+		},
+		{
+			"does not expand escaped variables",
+			`FOO="foo\$BAR"`,
+			map[string]string{"FOO": "foo$BAR"},
+		},
+		{
+			"does not expand escaped variables",
+			`FOO="foo\${BAR}"`,
+			map[string]string{"FOO": "foo${BAR}"},
+		},
+		{
+			"does not expand escaped variables",
+			"FOO=test\nBAR=\"foo\\${FOO} ${FOO}\"",
+			map[string]string{"FOO": "test", "BAR": "foo${FOO} test"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			env, err := Parse(strings.NewReader(tt.input))
+			if err != nil {
+				t.Errorf("Error: %s", err.Error())
+			}
+			for k, v := range tt.expected {
+				if strings.Compare(env[k], v) != 0 {
+					t.Errorf("Expected: %s, Actual: %s", v, env[k])
+				}
+			}
+		})
+	}
+
+}
+
 func TestActualEnvVarsAreLeftAlone(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("OPTION_A", "actualenv")
@@ -187,30 +290,46 @@ 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 single quotes inside double quotes
+	parseAndCompare(t, `FOO="'d'"`, "FOO", `'d'`)
 
 	// parses yaml style options
 	parseAndCompare(t, "OPTION_A: 1", "OPTION_A", "1")
 
+	//parses yaml values with equal signs
+	parseAndCompare(t, "OPTION_A: Foo=bar", "OPTION_A", "Foo=bar")
+
+	// parses non-yaml options with colons
+	parseAndCompare(t, "OPTION_A=1:B", "OPTION_A", "1:B")
+
 	// 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")
+	parseAndCompare(t, "export exportFoo=2", "exportFoo", "2")
+	parseAndCompare(t, "exportFOO=2", "exportFOO", "2")
+	parseAndCompare(t, "export_FOO =2", "export_FOO", "2")
+	parseAndCompare(t, "export.FOO= 2", "export.FOO", "2")
+	parseAndCompare(t, "export\tOPTION_A=2", "OPTION_A", "2")
+	parseAndCompare(t, "  export OPTION_A=2", "OPTION_A", "2")
+	parseAndCompare(t, "\texport OPTION_A=2", "OPTION_A", "2")
 
 	// 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
+	// it 'parses variables with "." in the name' do
 	// expect(env('FOO.BAR=foobar')).to eql('FOO.BAR' => 'foobar')
 	parseAndCompare(t, "FOO.BAR=foobar", "FOO.BAR", "foobar")
 
-	// it 'parses varibales with several "=" in the value' do
+	// it 'parses variables with several "=" in the value' do
 	// expect(env('FOO=foobar=')).to eql('FOO' => 'foobar=')
 	parseAndCompare(t, "FOO=foobar=", "FOO", "foobar=")
 
@@ -224,20 +343,34 @@ 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")
 
+	//newlines and backslashes should be escaped
+	parseAndCompare(t, `FOO="bar\n\ b\az"`, "FOO", "bar\n baz")
+	parseAndCompare(t, `FOO="bar\\\n\ b\az"`, "FOO", "bar\\\n baz")
+	parseAndCompare(t, `FOO="bar\\r\ b\az"`, "FOO", "bar\\r baz")
+
+	parseAndCompare(t, `="value"`, "", "value")
+	parseAndCompare(t, `KEY="`, "KEY", "\"")
+	parseAndCompare(t, `KEY="value`, "KEY", "\"value")
+
+	// leading whitespace should be ignored
+	parseAndCompare(t, " KEY =value", "KEY", "value")
+	parseAndCompare(t, "   KEY=value", "KEY", "value")
+	parseAndCompare(t, "\tKEY=value", "KEY", "value")
+
 	// it 'throws an error if line format is incorrect' do
 	// expect{env('lol$wut')}.to raise_error(Dotenv::FormatError)
 	badlyFormattedLine := "lol$wut"
-	_, _, err := parseLine(badlyFormattedLine)
+	_, _, err := parseLine(badlyFormattedLine, noopPresets)
 	if err == nil {
 		t.Errorf("Expected \"%v\" to return error, but it didn't", badlyFormattedLine)
 	}
@@ -250,6 +383,10 @@ func TestLinesToIgnore(t *testing.T) {
 		t.Error("Line with nothing but line break wasn't ignored")
 	}
 
+	if !isIgnoredLine("\r\n") {
+		t.Error("Line with nothing but windows-style line break wasn't ignored")
+	}
+
 	if !isIgnoredLine("\t\t ") {
 		t.Error("Line full of whitespace wasn't ignored")
 	}
@@ -265,7 +402,7 @@ 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")
 	}
 }
@@ -286,3 +423,52 @@ func TestErrorParsing(t *testing.T) {
 		t.Errorf("Expected error, got %v", envMap)
 	}
 }
+
+func TestWrite(t *testing.T) {
+	writeAndCompare := func(env string, expected string) {
+		envMap, _ := Unmarshal(env)
+		actual, _ := Marshal(envMap)
+		if expected != actual {
+			t.Errorf("Expected '%v' (%v) to write as '%v', got '%v' instead.", env, envMap, expected, actual)
+		}
+	}
+	//just test some single lines to show the general idea
+	//TestRoundtrip makes most of the good assertions
+
+	//values are always double-quoted
+	writeAndCompare(`key=value`, `key="value"`)
+	//double-quotes are escaped
+	writeAndCompare(`key=va"lu"e`, `key="va\"lu\"e"`)
+	//but single quotes are left alone
+	writeAndCompare(`key=va'lu'e`, `key="va'lu'e"`)
+	// newlines, backslashes, and some other special chars are escaped
+	writeAndCompare(`foo="\n\r\\r!"`, `foo="\n\r\\r\!"`)
+	// lines should be sorted
+	writeAndCompare("foo=bar\nbaz=buzz", "baz=\"buzz\"\nfoo=\"bar\"")
+	// integers should not be quoted
+	writeAndCompare(`key="10"`, `key=10`)
+
+}
+
+func TestRoundtrip(t *testing.T) {
+	fixtures := []string{"equals.env", "exported.env", "plain.env", "quoted.env"}
+	for _, fixture := range fixtures {
+		fixtureFilename := fmt.Sprintf("fixtures/%s", fixture)
+		env, err := readFile(fixtureFilename)
+		if err != nil {
+			t.Errorf("Expected '%s' to read without error (%v)", fixtureFilename, err)
+		}
+		rep, err := Marshal(env)
+		if err != nil {
+			t.Errorf("Expected '%s' to Marshal (%v)", fixtureFilename, err)
+		}
+		roundtripped, err := Unmarshal(rep)
+		if err != nil {
+			t.Errorf("Expected '%s' to Mashal and Unmarshal (%v)", fixtureFilename, err)
+		}
+		if !reflect.DeepEqual(env, roundtripped) {
+			t.Errorf("Expected '%s' to roundtrip as '%v', got '%v' instead", fixtureFilename, env, roundtripped)
+		}
+
+	}
+}