using valid env var with incorrect type function gives relevant panic msg

Author: bjubes

configurator.go

@@ -23,7 +23,7 @@ type Configurator interface {
 func GetEnvString(config Configurator, field string) string {
 	defer func() {
 		if r := recover(); r != nil {
-			log.Panicf("configurator has no field named '%s'", field)
+			log.Panicf("configurator has no string field named '%s'", field)
 		}
 	}()
 	value, exists := os.LookupEnv(field)
@@ -38,6 +38,9 @@ func GetEnvString(config Configurator, field string) string {
 func GetEnvBool(config Configurator, field string) bool {
 	defer func() {
 		if r := recover(); r != nil {
+			if reflect.ValueOf(config).FieldByName(field).IsValid() {
+				log.Panicf("configurator field '%s' is not a bool", field)
+			}
 			log.Panicf("configurator has no field named '%s'", field)
 		}
 	}()
@@ -53,6 +56,9 @@ func GetEnvBool(config Configurator, field string) bool {
 func GetEnvInt(config Configurator, field string) int {
 	defer func() {
 		if r := recover(); r != nil {
+			if reflect.ValueOf(config).FieldByName(field).IsValid() {
+				log.Panicf("configurator field '%s' is not an int", field)
+			}
 			log.Panicf("configurator has no field named '%s'", field)
 		}
 	}()
@@ -68,6 +74,9 @@ func GetEnvInt(config Configurator, field string) int {
 func GetEnvFloat(config Configurator, field string) float64 {
 	defer func() {
 		if r := recover(); r != nil {
+			if reflect.ValueOf(config).FieldByName(field).IsValid() {
+				log.Panicf("configurator field '%s' is not a float", field)
+			}
 			log.Panicf("configurator has no field named '%s'", field)
 		}
 	}()

configurator_test.go

@@ -244,6 +244,47 @@ func TestPanicMessageIncludesFieldName(t *testing.T) {
 	panicCheck(func() { config_iface.GetEnvBool("DOES_NOT_EXIST") })
 }
 
+func TestPanicOnExistingFieldWrongType(t *testing.T) {
+	var field_name, field_type string
+	panicCheck := func(f func()) {
+		defer func() {
+			r := recover()
+			if r == nil {
+				t.Errorf("Reading field using wrong type did not cause panic")
+			} else {
+				switch v := r.(type) {
+				case string:
+					if !strings.Contains(v, field_name) {
+						t.Errorf("Panic msg should contain field name '%s'. Got '%v'", field_name, r)
+					}
+					if !strings.Contains(v, field_type) {
+						t.Errorf("Panic msg should contain field type. Got '%v'", r)
+					}
+				case error:
+					if !strings.Contains(v.Error(), "DOES_NOT_EXIST") {
+						t.Errorf("Panic msg should contain field name '%s'. Got '%v'", field_name, r)
+					}
+					if !strings.Contains(v.Error(), field_type) {
+						t.Errorf("Panic msg should contain field type. Got '%v'", r)
+					}
+				default:
+					t.Errorf("Panic's type is unkown. Cannot check error msg. Type is '%T'", r)
+				}
+			}
+		}()
+		f()
+	}
+	field_name = "DB_HOST"
+	field_type = "int"
+	panicCheck(func() { config_iface.GetEnvInt("DB_HOST") })
+	field_type = "float"
+	panicCheck(func() { config_iface.GetEnvFloat("DB_HOST") })
+	field_type = "bool"
+	panicCheck(func() { config_iface.GetEnvBool("DB_HOST") })
+	field_name = "DB_PORT"
+	field_type = "string"
+	panicCheck(func() { config_iface.GetEnvString("DB_PORT") })
+}
 func use(vals ...any) {
 	for _, val := range vals {
 		_ = val