Wrap verbose and disabled in setters/getters

Turns out, we shouldn't set these from the environment in an init() function.  This gets called before consuming code has a chance to run anything, so other code doesn't have a chance to make changes to the environment before its read.  So for example, code using a library to load a .env file can't get that done before this package's init() function would be called.

So now we put these variables behind getters which lazily read these settings from the environment.

Author: Russ Egan

v2/flumetest/flumetest.go

@@ -26,17 +26,53 @@ import (
 	"github.com/ThalesGroup/flume/v2"
 )
 
-var Disable bool
-var Verbose bool
-
-//nolint:gochecknoinits
-func init() {
-	if s, ok := os.LookupEnv("FLUMETEST_DISABLE"); ok {
-		Disable, _ = strconv.ParseBool(s)
-	} else {
-		Disable, _ = strconv.ParseBool(os.Getenv("FLUME_TEST_DISABLE"))
-	}
-	Verbose, _ = strconv.ParseBool(os.Getenv("FLUMETEST_VERBOSE"))
+var (
+	disabledPtr *bool
+	verbosePtr  *bool
+
+	initializeOnce sync.Once
+)
+
+func Disabled() bool {
+	initialize()
+	return disabledPtr != nil && *disabledPtr
+}
+
+func SetDisabled(disabled bool) {
+	*disabledPtr = disabled
+}
+
+func Verbose() bool {
+	initialize()
+	return verbosePtr != nil && *verbosePtr
+}
+
+func SetVerbose(verbose bool) {
+	*verbosePtr = verbose
+}
+
+// do not read the environment in init().  Using init() to the read the environment
+// doesn't give consumers a chance to load .env files first, or otherwise set up
+// the environment.
+func initialize() {
+	initializeOnce.Do(func() {
+		// only read these from the env if they weren't already set by from the command
+		// line args
+		if disabledPtr == nil {
+			var b bool
+			if s, ok := os.LookupEnv("FLUMETEST_DISABLE"); ok {
+				b, _ = strconv.ParseBool(s)
+			} else {
+				b, _ = strconv.ParseBool(os.Getenv("FLUME_TEST_DISABLE"))
+			}
+			disabledPtr = &b
+		}
+		if verbosePtr == nil {
+			var b bool
+			b, _ = strconv.ParseBool(os.Getenv("FLUMETEST_VERBOSE"))
+			verbosePtr = &b
+		}
+	})
 }
 
 // RegisterFlags registers command line flag options related flume:
@@ -48,8 +84,8 @@ func init() {
 //
 // If you wish to use these flags in your tests, you should call this in TestMain().
 func RegisterFlags() {
-	flag.BoolVar(&Disable, "disable-flumetest", false, "Disables all flumetest features: logging will happen as normal")
-	flag.BoolVar(&Verbose, "vv", false, "During tests, forwards all logs immediately to t.Log()")
+	disabledPtr = flag.Bool("disable-flumetest", false, "Disables all flumetest features: logging will happen as normal")
+	verbosePtr = flag.Bool("vv", false, "During tests, forwards all logs immediately to t.Log()")
 }
 
 // Start captures all logs written during the test.  If the test succeeds, the
@@ -70,13 +106,13 @@ func RegisterFlags() {
 // useful to flush ear logs from setup code, then starting a new buffer for the
 // body of the test.
 func Start(t testingTB) func() {
-	if Disable {
+	if Disabled() {
 		// no op
 		return func() {}
 	}
 
 	revertToSnapshot := Snapshot(flume.Default())
-	if Verbose {
+	if Verbose() {
 		t.Cleanup(revertToSnapshot)
 		flume.Default().SetOut(flume.LogFuncWriter(t.Log, true))
 		return revertToSnapshot

v2/flumetest/flumetest_test.go

@@ -122,7 +122,7 @@ func TestStart(t *testing.T) {
 			failTest: false,
 			expect:   "color=red",
 			testFunc: func(tb testingTB) {
-				Verbose = true
+				SetVerbose(true)
 				Start(tb)
 
 				log.Info("Hi", "color", "red")
@@ -133,7 +133,7 @@ func TestStart(t *testing.T) {
 			failTest: true,
 			expect:   "",
 			testFunc: func(tb testingTB) {
-				Disable = true
+				SetDisabled(true)
 				Start(tb)
 
 				log.Info("Hi", "color", "red")
@@ -167,11 +167,11 @@ func TestStart(t *testing.T) {
 			}
 
 			// restore the original values after the test
-			oldDisabled := Disable
-			oldVerbose := Verbose
+			oldDisabled := Disabled()
+			oldVerbose := Verbose()
 			defer func() {
-				Disable = oldDisabled
-				Verbose = oldVerbose
+				SetDisabled(oldDisabled)
+				SetVerbose(oldVerbose)
 			}()
 
 			m := mockT{