✨ [environment] Add GetEnvironmentVariable() to try and fetch specific environment variable

changes/20231010151706.feature

@@ -0,0 +1 @@
+:sparkles: [`environment`] Add `GetEnvironmentVariable()` to fetch a specific environment variable

changes/20231010151811.feature

@@ -0,0 +1 @@
+:sparkles: [`environment`]  Extend `GetEnvironmentVariables()` to accept optional ...dotEnvFiles so that [.env](https://github.com/bkeepers/dotenv) files can be loaded into the current environment

utils/environment/current.go

@@ -1,11 +1,14 @@
 package environment
 
 import (
+	"fmt"
 	"os"
 	"os/user"
 
+	"github.com/joho/godotenv"
 	"github.com/mitchellh/go-homedir"
 
+	"github.com/ARM-software/golang-utils/utils/commonerrors"
 	"github.com/ARM-software/golang-utils/utils/filesystem"
 )
 
@@ -25,7 +28,13 @@ func (c *currentEnv) GetCurrentUser() (currentUser *user.User) {
 	return
 }
 
-func (c *currentEnv) GetEnvironmentVariables() (variables []IEnvironmentVariable) {
+// GetEnvironmentVariables returns the current environment variable (and optionally those in the supplied in `dotEnvFiles`)
+// `dotEnvFiles` corresponds to `.env` files present on the machine and follows the mechanism described by https://github.com/bkeepers/dotenv
+func (c *currentEnv) GetEnvironmentVariables(dotEnvFiles ...string) (variables []IEnvironmentVariable) {
+	if len(dotEnvFiles) > 0 { // if no args, then it will attempt to load .env
+		_ = godotenv.Load(dotEnvFiles...) // ignore error (specifically on loading .env) consistent with config.LoadFromEnvironment
+	}
+
 	curentEnv := os.Environ()
 	for i := range curentEnv {
 		envvar, err := ParseEnvironmentVariable(curentEnv[i])
@@ -41,6 +50,17 @@ func (c *currentEnv) GetFilesystem() filesystem.FS {
 	return filesystem.NewStandardFileSystem()
 }
 
+// GetEnvironmentVariable searches the current environment (and optionally dotEnvFiles) for a specific environment variable `envvar`.
+func (c *currentEnv) GetEnvironmentVariable(envvar string, dotEnvFiles ...string) (value IEnvironmentVariable, err error) {
+	envvars := c.GetEnvironmentVariables(dotEnvFiles...)
+	for i := range envvars {
+		if envvars[i].GetKey() == envvar {
+			return envvars[i], nil
+		}
+	}
+	return nil, fmt.Errorf("%w: environment variable '%v' not set", commonerrors.ErrNotFound, envvar)
+}
+
 // NewCurrentEnvironment returns system current environment.
 func NewCurrentEnvironment() IEnvironment {
 	return &currentEnv{}

utils/environment/current_test.go

@@ -1,12 +1,21 @@
 package environment
 
 import (
+	"fmt"
 	"os"
 	"testing"
 
 	"github.com/bxcodec/faker/v3"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/ARM-software/golang-utils/utils/commonerrors"
+	"github.com/ARM-software/golang-utils/utils/commonerrors/errortest"
+	"github.com/ARM-software/golang-utils/utils/filesystem"
+)
+
+const (
+	dotEnvPattern = ".env.*"
 )
 
 func TestNewCurrentEnvironment(t *testing.T) {
@@ -20,11 +29,129 @@ func TestNewCurrentEnvironment(t *testing.T) {
 }
 
 func Test_currentEnv_GetEnvironmentVariables(t *testing.T) {
-	os.Clearenv()
-	require.NoError(t, os.Setenv("test1", faker.Sentence()))
-	require.NoError(t, os.Setenv("test2", faker.Sentence()))
-	current := NewCurrentEnvironment()
-	envVars := current.GetEnvironmentVariables()
-	assert.Len(t, envVars, 2)
-	assert.False(t, envVars[0].Equal(envVars[1]))
+	t.Run("No dotenv files", func(t *testing.T) {
+		os.Clearenv()
+		require.NoError(t, os.Setenv("test1", faker.Sentence()))
+		require.NoError(t, os.Setenv("test2", faker.Sentence()))
+		current := NewCurrentEnvironment()
+		envVars := current.GetEnvironmentVariables()
+		assert.Len(t, envVars, 2)
+		assert.False(t, envVars[0].Equal(envVars[1]))
+	})
+
+	t.Run("With dotenv files", func(t *testing.T) {
+		os.Clearenv()
+		require.NoError(t, os.Setenv("test1", faker.Sentence()))
+		require.NoError(t, os.Setenv("test2", faker.Sentence()))
+
+		dotenv1, err := filesystem.TempFileInTempDir(dotEnvPattern)
+		require.NoError(t, err)
+		defer func() { _ = dotenv1.Close() }()
+		test3 := NewEnvironmentVariable("test3", faker.Sentence())
+		_, err = dotenv1.WriteString(test3.String())
+		require.NoError(t, err)
+		err = dotenv1.Close()
+		require.NoError(t, err)
+
+		dotenv2, err := filesystem.TempFileInTempDir(dotEnvPattern)
+		require.NoError(t, err)
+		defer func() { _ = dotenv2.Close() }()
+		test4 := NewEnvironmentVariable("test4", faker.Sentence())
+		_, err = dotenv2.WriteString(fmt.Sprintf("%v\n", test4.String()))
+		require.NoError(t, err)
+		test5 := NewEnvironmentVariable("test5", faker.Sentence())
+		_, err = dotenv2.WriteString(fmt.Sprintf("%v\n", test5.String()))
+		require.NoError(t, err)
+		err = dotenv2.Close()
+		require.NoError(t, err)
+
+		current := NewCurrentEnvironment()
+		envVars := current.GetEnvironmentVariables(dotenv1.Name(), dotenv2.Name())
+		assert.Len(t, envVars, 5)
+		assert.False(t, envVars[0].Equal(envVars[1]))
+		assert.True(t, envVars[2].Equal(test3))
+		assert.True(t, envVars[3].Equal(test4))
+		assert.True(t, envVars[4].Equal(test5))
+	})
+}
+
+func Test_currentenv_GetEnvironmentVariable(t *testing.T) {
+	t.Run("Env var exists", func(t *testing.T) {
+		os.Clearenv()
+		test := NewEnvironmentVariable(faker.Word(), faker.Sentence())
+		require.NoError(t, os.Setenv(test.GetKey(), test.GetValue()))
+
+		current := NewCurrentEnvironment()
+
+		actual, err := current.GetEnvironmentVariable(test.GetKey())
+		assert.NoError(t, err)
+		assert.Equal(t, test, actual)
+	})
+
+	t.Run("Env var not exists", func(t *testing.T) {
+		os.Clearenv()
+		test := NewEnvironmentVariable(faker.Word(), faker.Sentence())
+		current := NewCurrentEnvironment()
+
+		actual, err := current.GetEnvironmentVariable(faker.Word())
+		errortest.AssertError(t, err, commonerrors.ErrNotFound)
+		assert.NotEqual(t, test, actual)
+	})
+
+	t.Run("With dotenv files", func(t *testing.T) {
+		os.Clearenv()
+		test1 := NewEnvironmentVariable("test1", faker.Sentence())
+		test2 := NewEnvironmentVariable("test2", faker.Sentence())
+
+		require.NoError(t, os.Setenv(test1.GetKey(), test1.GetValue()))
+		require.NoError(t, os.Setenv(test2.GetKey(), test2.GetValue()))
+
+		dotenv1, err := filesystem.TempFileInTempDir(dotEnvPattern)
+		require.NoError(t, err)
+		defer func() { _ = dotenv1.Close() }()
+		test3 := NewEnvironmentVariable("test3", faker.Sentence())
+		_, err = dotenv1.WriteString(test3.String())
+		require.NoError(t, err)
+		err = dotenv1.Close()
+		require.NoError(t, err)
+
+		dotenv2, err := filesystem.TempFileInTempDir(dotEnvPattern)
+		require.NoError(t, err)
+		defer func() { _ = dotenv2.Close() }()
+		test4 := NewEnvironmentVariable("test4", faker.Sentence())
+		_, err = dotenv2.WriteString(fmt.Sprintf("%v\n", test4.String()))
+		require.NoError(t, err)
+		test5 := NewEnvironmentVariable("test5", faker.Sentence())
+		_, err = dotenv2.WriteString(fmt.Sprintf("%v\n", test5.String()))
+		require.NoError(t, err)
+		err = dotenv2.Close()
+		require.NoError(t, err)
+
+		current := NewCurrentEnvironment()
+		test1Actual, err := current.GetEnvironmentVariable(test1.GetKey(), dotenv1.Name(), dotenv2.Name())
+		assert.NoError(t, err)
+		assert.Equal(t, test1, test1Actual)
+		test2Actual, err := current.GetEnvironmentVariable(test2.GetKey(), dotenv1.Name(), dotenv2.Name())
+		assert.NoError(t, err)
+		assert.Equal(t, test2, test2Actual)
+		test3Actual, err := current.GetEnvironmentVariable(test3.GetKey(), dotenv1.Name(), dotenv2.Name())
+		assert.NoError(t, err)
+		assert.Equal(t, test3, test3Actual)
+		test4Actual, err := current.GetEnvironmentVariable(test4.GetKey(), dotenv1.Name(), dotenv2.Name())
+		assert.NoError(t, err)
+		assert.Equal(t, test4, test4Actual)
+		test5Actual, err := current.GetEnvironmentVariable(test5.GetKey(), dotenv1.Name(), dotenv2.Name())
+		assert.NoError(t, err)
+		assert.Equal(t, test5, test5Actual)
+
+		os.Clearenv()
+
+		test3Missing, err := current.GetEnvironmentVariable(test3.GetKey(), dotenv2.Name())
+		errortest.AssertError(t, err, commonerrors.ErrNotFound)
+		assert.NotEqual(t, test3, test3Missing)
+
+		testMissing, err := current.GetEnvironmentVariable(faker.Word(), dotenv1.Name(), dotenv2.Name())
+		errortest.AssertError(t, err, commonerrors.ErrNotFound)
+		assert.Nil(t, testMissing)
+	})
 }

utils/environment/interfaces.go

@@ -30,8 +30,12 @@ type IEnvironmentVariable interface {
 type IEnvironment interface {
 	// GetCurrentUser returns the environment current user.
 	GetCurrentUser() *user.User
-	// GetEnvironmentVariables returns the variables defining the environment.
-	GetEnvironmentVariables() []IEnvironmentVariable
+	// GetEnvironmentVariables returns the variables defining the environment  (and optionally those supplied in `dotEnvFiles`)
+	// `dotEnvFiles` corresponds to `.env` files present on the machine and follows the mechanism described by https://github.com/bkeepers/dotenv
+	GetEnvironmentVariables(dotEnvFiles ...string) []IEnvironmentVariable
 	// GetFilesystem returns the filesystem associated with the current environment
 	GetFilesystem() filesystem.FS
+	// GetEnvironmentVariable returns the environment variable corresponding to `envvar` or an error if it not set. optionally it searches `dotEnvFiles` files too
+	// `dotEnvFiles` corresponds to `.env` files present on the machine and follows the mechanism described by https://github.com/bkeepers/dotenv
+	GetEnvironmentVariable(envvar string, dotEnvFiles ...string) (IEnvironmentVariable, error)
 }