From c2116b41944a93870cbf8d8b207523ec2e98efc8 Mon Sep 17 00:00:00 2001
From: ccoVeille <3875889+ccoVeille@users.noreply.github.com>
Date: Thu, 8 May 2025 15:44:35 +0200
Subject: [PATCH] Improve ErrorAs failure message when error is nil

Before:

    Should be in error chain:
    expected: *assert.customError
    in chain:

After:
    An error is expected but got nil.
    expected: *assert.customError

The message `An error is expected but got nil.` is the one already
reported by `assert.Error`
---
 assert/assertions.go      | 8 +++++++-
 assert/assertions_test.go | 5 ++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/assert/assertions.go b/assert/assertions.go
index 0ed1eed09..3353b33a2 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -2202,11 +2202,17 @@ func ErrorAs(t TestingT, err error, target interface{}, msgAndArgs ...interface{
 		return true
 	}
 
+	expectedText := reflect.ValueOf(target).Elem().Type().String()
+	if err == nil {
+		return Fail(t, fmt.Sprintf("An error is expected but got nil.\n"+
+			"expected: %s", expectedText), msgAndArgs...)
+	}
+
 	chain := buildErrorChainString(err, true)
 
 	return Fail(t, fmt.Sprintf("Should be in error chain:\n"+
 		"expected: %s\n"+
-		"in chain: %s", reflect.ValueOf(target).Elem().Type(), chain,
+		"in chain: %s", expectedText, chain,
 	), msgAndArgs...)
 }
 
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index 16dc2587d..77a151856 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -3402,9 +3402,8 @@ func TestErrorAs(t *testing.T) {
 			err:    nil,
 			result: false,
 			resultErrMsg: "" +
-				"Should be in error chain:\n" +
-				"expected: *assert.customError\n" +
-				"in chain: \n",
+				"An error is expected but got nil.\n" +
+				`expected: *assert.customError` + "\n",
 		},
 		{
 			err:    fmt.Errorf("abc: %w", errors.New("def")),