Allow setting official check mode configuration via environment variable

Since the official mode should only be used when checking official Arduino projects, I thought it was not a good idea to
add a flag for this setting, since it could cause confusion to the those using the tool to check 3rd party projects, who
have no use for this setting.

Author: per1234

README.md

@@ -9,3 +9,6 @@
 ## Usage
 
 After installing `arduino-check`, run the command `arduino-check --help` for usage documentation.
+
+Set the `ARDUINO_CHECK_OFFICIAL` environment variable to "true" to run the checks that only apply to official Arduino
+projects.

configuration/checkmode/checkmode.go

@@ -51,6 +51,18 @@ func LibraryManagerModeFromString(libraryManagerModeString string) (bool, bool,
 	}
 }
 
+// OfficialModeFromString parses the ARDUINO_CHECK_OFFICIAL environment variable value and returns the corresponding check mode setting.
+func OfficialModeFromString(officialModeString string) (bool, error) {
+	switch strings.ToLower(officialModeString) {
+	case "true":
+		return true, nil
+	case "false":
+		return false, nil
+	default:
+		return false, fmt.Errorf("No matching official check mode for string %s", officialModeString)
+	}
+}
+
 // Modes merges the default check mode values for the given superproject type with any user-specified check mode settings.
 func Modes(defaultCheckModes map[projecttype.Type]map[Type]bool, customCheckModes map[Type]bool, superprojectType projecttype.Type) map[Type]bool {
 	checkModes := make(map[Type]bool)

configuration/configuration.go

@@ -78,8 +78,13 @@ func Initialize(flags *pflag.FlagSet, projectPaths []string) error {
 	// TODO support multiple paths
 	targetPath = paths.New(projectPaths[0])
 
-	// TODO: set via environment variable
-	// customCheckModes[checkmode.Official] = false
+	officialModeString, officialModeEnvironmentVariableDefined := os.LookupEnv("ARDUINO_CHECK_OFFICIAL")
+	if officialModeEnvironmentVariableDefined {
+		customCheckModes[checkmode.Official], err = checkmode.OfficialModeFromString(officialModeString)
+		if err != nil {
+			return fmt.Errorf("ARDUINO_CHECK_OFFICIAL environment variable value %s not valid", officialModeString)
+		}
+	}
 
 	logrus.WithFields(logrus.Fields{
 		"output format":                   OutputFormat(),

configuration/configuration_test.go

@@ -16,6 +16,7 @@
 package configuration
 
 import (
+	"os"
 	"testing"
 
 	"github.com/arduino/arduino-check/configuration/checkmode"
@@ -129,4 +130,15 @@ func TestInitialize(t *testing.T) {
 	projectPaths = []string{reportFilePath.String()}
 	assert.Nil(t, Initialize(flags, projectPaths))
 	assert.Equal(t, reportFilePath, TargetPath())
+
+	os.Setenv("ARDUINO_CHECK_OFFICIAL", "true")
+	assert.Nil(t, Initialize(test.ConfigurationFlags(), projectPaths))
+	assert.True(t, customCheckModes[checkmode.Official])
+
+	os.Setenv("ARDUINO_CHECK_OFFICIAL", "false")
+	assert.Nil(t, Initialize(test.ConfigurationFlags(), projectPaths))
+	assert.False(t, customCheckModes[checkmode.Official])
+
+	os.Setenv("ARDUINO_CHECK_OFFICIAL", "invalid value")
+	assert.Error(t, Initialize(test.ConfigurationFlags(), projectPaths))
 }