From 84924ff9679e8c8e7dca5dd1d3ca390b4c08548b Mon Sep 17 00:00:00 2001
From: Thiago Gomes Bento Ferreira <thiagogbferreira@gmail.com>
Date: Mon, 12 Sep 2022 19:26:44 -0300
Subject: [PATCH] feat: added IsError test

---
 assert.go      | 18 ++++++++++++++++++
 assert_test.go |  7 +++++++
 2 files changed, 25 insertions(+)

diff --git a/assert.go b/assert.go
index a3a18ab..2eaec0b 100644
--- a/assert.go
+++ b/assert.go
@@ -1,6 +1,7 @@
 package assert
 
 import (
+	"errors"
 	"fmt"
 	"path"
 	"reflect"
@@ -166,6 +167,23 @@ func NotEqualSkip(t testing.TB, skip int, val1, val2 interface{}) {
 		t.FailNow()
 	}
 }
+// IsErrorSkip validates that any error in err's chain matches target
+// and throws an error with line number
+// but the skip variable tells IsErrorSkip how far back on the stack to report the error.
+// This is a building block to creating your own more complex validation functions.
+func IsErrorSkip(t testing.TB, skip int, err, target error) {
+	if !errors.Is(err, target) {
+		_, file, line, _ := runtime.Caller(skip)
+		fmt.Printf("%s:%d %v does not is %v\n", path.Base(file), line, err, target)
+		t.FailNow()
+	}
+}
+
+// IsError validates that any error in err's chain matches target
+// and throws an error with line number
+func IsError(t testing.TB, err, target error) {
+	IsErrorSkip(t, 2, err, target)
+}
 
 // PanicMatches validates that the panic output of running fn matches the supplied string
 func PanicMatches(t testing.TB, fn func(), matches string) {
diff --git a/assert_test.go b/assert_test.go
index 6362181..ace245f 100644
--- a/assert_test.go
+++ b/assert_test.go
@@ -3,6 +3,7 @@ package assert
 import (
 	"errors"
 	"testing"
+	"fmt"
 )
 
 // NOTES:
@@ -90,3 +91,9 @@ func TestEquals(t *testing.T) {
 	Equal(t, iface, 1)
 	NotEqual(t, iface, iface2)
 }
+
+func TestIsError(t *testing.T) {
+	err1 := errors.New("unknown error")
+	errWrapped := fmt.Errorf("another error: %w", err1)
+	IsError(t, errWrapped, err1)
+}