test: add examples for finder

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

finder_example_test.go

@@ -0,0 +1,75 @@
+//go:build viper_finder
+
+package viper_test
+
+import (
+	"fmt"
+
+	"github.com/sagikazarmark/locafero"
+	"github.com/spf13/afero"
+
+	"github.com/spf13/viper"
+)
+
+func ExampleFinder() {
+	fs := afero.NewMemMapFs()
+
+	fs.Mkdir("/home/user", 0o777)
+
+	f, _ := fs.Create("/home/user/myapp.yaml")
+	f.WriteString("foo: bar")
+	f.Close()
+
+	// HCL will have a "lower" priority in the search order
+	fs.Create("/home/user/myapp.hcl")
+
+	finder := locafero.Finder{
+		Paths: []string{"/home/user"},
+		Names: locafero.NameWithExtensions("myapp", viper.SupportedExts...),
+		Type:  locafero.FileTypeFile, // This is important!
+	}
+
+	v := viper.NewWithOptions(viper.WithFinder(finder))
+	v.SetFs(fs)
+	v.ReadInConfig()
+
+	fmt.Println(v.GetString("foo"))
+
+	// Output:
+	// bar
+}
+
+func ExampleFinders() {
+	fs := afero.NewMemMapFs()
+
+	fs.Mkdir("/home/user", 0o777)
+	f, _ := fs.Create("/home/user/myapp.yaml")
+	f.WriteString("foo: bar")
+	f.Close()
+
+	fs.Mkdir("/etc/myapp", 0o777)
+	fs.Create("/etc/myapp/config.yaml")
+
+	// Combine multiple finders to search for files in multiple locations with different criteria
+	finder := viper.Finders(
+		locafero.Finder{
+			Paths: []string{"/home/user"},
+			Names: locafero.NameWithExtensions("myapp", viper.SupportedExts...),
+			Type:  locafero.FileTypeFile, // This is important!
+		},
+		locafero.Finder{
+			Paths: []string{"/etc/myapp"},
+			Names: []string{"config.yaml"}, // Only accept YAML files in the system config directory
+			Type:  locafero.FileTypeFile,   // This is important!
+		},
+	)
+
+	v := viper.NewWithOptions(viper.WithFinder(finder))
+	v.SetFs(fs)
+	v.ReadInConfig()
+
+	fmt.Println(v.GetString("foo"))
+
+	// Output:
+	// bar
+}