Do envconfig-loading in config.go (and test it!) [#9]

cmd/drone-helm/main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"fmt"
-	"github.com/kelseyhightower/envconfig"
 	"os"
 
 	"github.com/pelotech/drone-helm3/internal/helm"
@@ -11,7 +10,7 @@ import (
 func main() {
 	var c helm.Config
 
-	if err := envconfig.Process("plugin", &c); err != nil {
+	if err := c.Populate(); err != nil {
 		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
 		return
 	}

internal/helm/config.go

@@ -1,6 +1,8 @@
 package helm
 
-import ()
+import (
+	"github.com/kelseyhightower/envconfig"
+)
 
 // The Config struct captures the `settings` and `environment` blocks in the application's drone
 // config. Configuration in drone's `settings` block arrives as uppercase env vars matching the
@@ -33,3 +35,8 @@ type Config struct {
 	Release            string   ``                                   // Release argument to use in applicable helm commands
 	Force              bool     ``                                   // Pass --force to applicable helm commands
 }
+
+// Populate reads environment variables into the Config.
+func (cfg *Config) Populate() error {
+	return envconfig.Process("plugin", cfg)
+}

internal/helm/config_test.go

@@ -2,13 +2,64 @@ package helm
 
 import (
 	"github.com/stretchr/testify/suite"
+	"os"
 	"testing"
 )
 
 type ConfigTestSuite struct {
 	suite.Suite
+	// These tests need to mutate the environment, so the suite.setenv and .unsetenv functions store the original contents of the
+	// relevant variable in this map. Its use of *string is so they can distinguish between "not set" and "set to empty string"
+	envBackup map[string]*string
 }
 
 func TestConfigTestSuite(t *testing.T) {
 	suite.Run(t, new(ConfigTestSuite))
 }
+
+func (suite *ConfigTestSuite) TestPopulateWithPluginPrefix() {
+	suite.setenv("PLUGIN_HELM_COMMAND", "execute order 66")
+	suite.setenv("PLUGIN_UPDATE_DEPENDENCIES", "true")
+	suite.setenv("PLUGIN_DEBUG", "true")
+
+	cfg := Config{}
+	cfg.Populate()
+
+	suite.Equal("execute order 66", cfg.Command)
+	suite.True(cfg.UpdateDependencies)
+	suite.True(cfg.Debug)
+}
+
+func (suite *ConfigTestSuite) setenv(key, val string) {
+	orig, ok := os.LookupEnv(key)
+	if ok {
+		suite.envBackup[key] = &orig
+	} else {
+		suite.envBackup[key] = nil
+	}
+	os.Setenv(key, val)
+}
+
+func (suite *ConfigTestSuite) unsetenv(key string) {
+	orig, ok := os.LookupEnv(key)
+	if ok {
+		suite.envBackup[key] = &orig
+	} else {
+		suite.envBackup[key] = nil
+	}
+	os.Unsetenv(key)
+}
+
+func (suite *ConfigTestSuite) BeforeTest(_, _ string) {
+	suite.envBackup = make(map[string]*string)
+}
+
+func (suite *ConfigTestSuite) AfterTest(_, _ string) {
+	for key, val := range suite.envBackup {
+		if val == nil {
+			os.Unsetenv(key)
+		} else {
+			os.Setenv(key, *val)
+		}
+	}
+}