From 7885e16b2cb0267bcc8b07cdd0eced14e8005864 Mon Sep 17 00:00:00 2001
From: Alexey Palazhchenko <alexey.palazhchenko@gmail.com>
Date: Fri, 14 May 2021 13:44:45 +0300
Subject: [PATCH] feat: add ExpectedErrorf

Convenient.

Signed-off-by: Alexey Palazhchenko <alexey.palazhchenko@gmail.com>
---
 retry/constant_test.go    | 10 +++++-----
 retry/exponential_test.go | 10 +++++-----
 retry/linear_test.go      | 10 +++++-----
 retry/retry.go            |  5 +++++
 4 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/retry/constant_test.go b/retry/constant_test.go
index 5bbe508..a40f016 100644
--- a/retry/constant_test.go
+++ b/retry/constant_test.go
@@ -42,7 +42,7 @@ func Test_constantRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 3,
@@ -60,7 +60,7 @@ func Test_constantRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 5,
@@ -99,7 +99,7 @@ func Test_constantRetryer_Retry(t *testing.T) {
 						return fmt.Errorf("unexpected")
 					}
 
-					return ExpectedError(fmt.Errorf("unexpected"))
+					return ExpectedErrorf("unexpected")
 				},
 			},
 			expectedCount: 2,
@@ -120,7 +120,7 @@ func Test_constantRetryer_Retry(t *testing.T) {
 						return nil
 					}
 
-					return ExpectedError(fmt.Errorf("unexpected"))
+					return ExpectedErrorf("unexpected")
 				},
 			},
 			expectedCount: 2,
@@ -154,7 +154,7 @@ func Test_constantRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 1,
diff --git a/retry/exponential_test.go b/retry/exponential_test.go
index c05c97f..ee2fca5 100644
--- a/retry/exponential_test.go
+++ b/retry/exponential_test.go
@@ -42,7 +42,7 @@ func Test_exponentialRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 4,
@@ -60,7 +60,7 @@ func Test_exponentialRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 5,
@@ -99,7 +99,7 @@ func Test_exponentialRetryer_Retry(t *testing.T) {
 						return fmt.Errorf("unexpected")
 					}
 
-					return ExpectedError(fmt.Errorf("unexpected"))
+					return ExpectedErrorf("unexpected")
 				},
 			},
 			expectedCount: 2,
@@ -120,7 +120,7 @@ func Test_exponentialRetryer_Retry(t *testing.T) {
 						return nil
 					}
 
-					return ExpectedError(fmt.Errorf("unexpected"))
+					return ExpectedErrorf("unexpected")
 				},
 			},
 			expectedCount: 2,
@@ -154,7 +154,7 @@ func Test_exponentialRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 2,
diff --git a/retry/linear_test.go b/retry/linear_test.go
index 1f608ca..21c66b3 100644
--- a/retry/linear_test.go
+++ b/retry/linear_test.go
@@ -42,7 +42,7 @@ func Test_linearRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 5,
@@ -60,7 +60,7 @@ func Test_linearRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 9,
@@ -99,7 +99,7 @@ func Test_linearRetryer_Retry(t *testing.T) {
 						return fmt.Errorf("unexpected")
 					}
 
-					return ExpectedError(fmt.Errorf("unexpected"))
+					return ExpectedErrorf("unexpected")
 				},
 			},
 			expectedCount: 1,
@@ -120,7 +120,7 @@ func Test_linearRetryer_Retry(t *testing.T) {
 						return nil
 					}
 
-					return ExpectedError(fmt.Errorf("unexpected"))
+					return ExpectedErrorf("unexpected")
 				},
 			},
 			expectedCount: 2,
@@ -154,7 +154,7 @@ func Test_linearRetryer_Retry(t *testing.T) {
 				f: func() error {
 					count++
 
-					return ExpectedError(fmt.Errorf("expected"))
+					return ExpectedErrorf("expected")
 				},
 			},
 			expectedCount: 1,
diff --git a/retry/retry.go b/retry/retry.go
index 60c81f4..788d72e 100644
--- a/retry/retry.go
+++ b/retry/retry.go
@@ -159,6 +159,11 @@ func ExpectedError(err error) error {
 	return expectedError{err}
 }
 
+// ExpectedErrorf makes an expected error from given format and arguments.
+func ExpectedErrorf(format string, a ...interface{}) error {
+	return ExpectedError(fmt.Errorf(format, a...))
+}
+
 // UnexpectedError error represents an error that is unexpected by the retrying
 // function. This error is fatal.
 //