From 85798776bfab15659066a6746bb2db9b020abe85 Mon Sep 17 00:00:00 2001
From: Leonidas Vrachnis <leo.al.vra@gmail.com>
Date: Mon, 8 Apr 2024 19:44:04 +0300
Subject: [PATCH] chore: provide methods to access config init errors (#406)

Co-authored-by: Francesco Casula <fracasula@users.noreply.github.com>
---
 config/config.go      |  3 +++
 config/config_test.go | 53 +++++++++++++++++++++++++++++++++++++++++++
 config/load.go        | 38 +++++++++++++++----------------
 3 files changed, 75 insertions(+), 19 deletions(-)

diff --git a/config/config.go b/config/config.go
index 401b70b4..72bc17b2 100644
--- a/config/config.go
+++ b/config/config.go
@@ -100,6 +100,9 @@ type Config struct {
 	reloadableVars          map[string]any
 	reloadableVarsMisuses   map[string]string
 	reloadableVarsLock      sync.RWMutex // used to protect both the reloadableVars and reloadableVarsMisuses maps
+	configPath              string
+	configPathErr           error
+	godotEnvErr             error
 }
 
 // GetBool gets bool value from config
diff --git a/config/config_test.go b/config/config_test.go
index 9dbb62eb..94db77d5 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -3,6 +3,7 @@ package config
 import (
 	"context"
 	"fmt"
+	"os"
 	"sync"
 	"testing"
 	"time"
@@ -516,6 +517,15 @@ func TestGetEnvThroughViper(t *testing.T) {
 		require.Equal(t, expectedValue, tc.GetString("Key.Var1VarVar", ""))
 	})
 
+	t.Run("with env prefix", func(t *testing.T) {
+		envPrefix := "ANOTHER_PREFIX"
+
+		tc := New(WithEnvPrefix(envPrefix))
+		t.Setenv(envPrefix+"_KEY_VAR1_VAR_VAR", expectedValue)
+
+		require.Equal(t, expectedValue, tc.GetString("Key.Var1VarVar", ""))
+	})
+
 	t.Run("detects uppercase env variables", func(t *testing.T) {
 		t.Setenv("SOMEENVVARIABLE", expectedValue)
 		tc := New()
@@ -671,3 +681,46 @@ func TestConfigLocking(t *testing.T) {
 
 	require.NoError(t, g.Wait())
 }
+
+func TestConfigLoad(t *testing.T) {
+	// create a temporary file:
+	f, err := os.CreateTemp("", "*config.yaml")
+	require.NoError(t, err)
+	defer os.Remove(f.Name())
+
+	t.Setenv("CONFIG_PATH", f.Name())
+	c := New()
+	require.NoError(t, err)
+
+	t.Run("successfully loaded config file", func(t *testing.T) {
+		configFile, err := c.ConfigFileUsed()
+		require.NoError(t, err)
+		require.Equal(t, f.Name(), configFile)
+	})
+
+	err = os.Remove(f.Name())
+	require.NoError(t, err)
+
+	t.Run("attempt to load non-existent config file", func(t *testing.T) {
+		c := New()
+		configFile, err := c.ConfigFileUsed()
+		require.Error(t, err)
+		require.Equal(t, f.Name(), configFile)
+	})
+
+	t.Run("dot env error", func(t *testing.T) {
+		c := New()
+		err := c.DotEnvLoaded()
+		require.Error(t, err)
+	})
+
+	t.Run("dot env found", func(t *testing.T) {
+		c := New()
+		f, err := os.Create(".env")
+		require.NoError(t, err)
+		defer os.Remove(f.Name())
+
+		err = c.DotEnvLoaded()
+		require.Error(t, err)
+	})
+}
diff --git a/config/load.go b/config/load.go
index 439a9916..e6698847 100644
--- a/config/load.go
+++ b/config/load.go
@@ -2,9 +2,7 @@ package config
 
 import (
 	"fmt"
-	"os"
 	"reflect"
-	"strings"
 	"time"
 
 	"github.com/fsnotify/fsnotify"
@@ -17,9 +15,7 @@ func (c *Config) load() {
 	c.hotReloadableConfig = make(map[string][]*configValue)
 	c.envs = make(map[string]string)
 
-	if err := godotenv.Load(); err != nil && !isTest() {
-		fmt.Println("INFO: No .env file found.")
-	}
+	c.godotEnvErr = godotenv.Load()
 
 	configPath := getEnv("CONFIG_PATH", "./config/config.yaml")
 
@@ -28,11 +24,12 @@ func (c *Config) load() {
 	bindLegacyEnv(v)
 
 	v.SetConfigFile(configPath)
-	err := v.ReadInConfig() // Find and read the config file
-	// Don't panic if config.yaml is not found or error with parsing. Use the default config values instead
-	if err != nil && !isTest() {
-		fmt.Printf("[Config] :: Failed to parse config file from path %q, using default values: %v\n", configPath, err)
-	}
+
+	// Find and read the config file
+	// If config.yaml is not found or error with parsing. Use the default config values instead
+	c.configPathErr = v.ReadInConfig()
+	c.configPath = v.ConfigFileUsed()
+
 	v.OnConfigChange(func(e fsnotify.Event) {
 		c.onConfigChange()
 	})
@@ -41,6 +38,18 @@ func (c *Config) load() {
 	c.v = v
 }
 
+// ConfigFileUsed returns the file used to load the config.
+// If we failed to load the config file, it also returns an error.
+func (c *Config) ConfigFileUsed() (string, error) {
+	return c.configPath, c.configPathErr
+}
+
+// DotEnvLoaded returns an error if there was an error loading the .env file.
+// It returns nil otherwise.
+func (c *Config) DotEnvLoaded() error {
+	return c.godotEnvErr
+}
+
 func (c *Config) onConfigChange() {
 	defer func() {
 		if r := recover(); r != nil {
@@ -230,12 +239,3 @@ func mapDeepEqual[K comparable, V any](a, b map[K]V) bool {
 	}
 	return true
 }
-
-func isTest() bool {
-	for _, arg := range os.Args {
-		if strings.HasPrefix(arg, "-test.") {
-			return true
-		}
-	}
-	return false
-}