lib/errors: implement method Is

The Is method will return true if the target error is instance of *E
and the value of field Code and Name match with values in e.

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/errors/errors_example_test.go b/lib/errors/errors_example_test.go
new file mode 100644
index 00000000..84d1de2e
--- /dev/null
+++ b/lib/errors/errors_example_test.go
@@ -0,0 +1,44 @@
+package errors_test
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log"
+
+	liberrors "github.com/shuLhan/share/lib/errors"
+)
+
+func ExampleErrors_Is() {
+	var (
+		errFileNotFound = &liberrors.E{
+			Code:    400,
+			Name:    `ERR_NOT_FOUND`,
+			Message: `file not found`,
+		}
+		errResNotFound = &liberrors.E{
+			Code:    404,
+			Name:    `ERR_NOT_FOUND`,
+			Message: `resource not found`,
+		}
+
+		rawJson = `{"code":400,"name":"ERR_NOT_FOUND","message":"file not found"}`
+
+		e   *liberrors.E
+		err error
+	)
+
+	err = json.Unmarshal([]byte(rawJson), &e)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var gotErr error = e
+
+	fmt.Println(errors.Is(gotErr, errFileNotFound))
+	fmt.Println(errors.Is(gotErr, errResNotFound))
+
+	// Output:
+	// true
+	// false
+}