retry.go

Documentation: cloud.google.com/go/internal/testutil

     1  // Copyright 2019 Google LLC
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     https://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package testutil
    16  
    17  import (
    18  	"bytes"
    19  	"fmt"
    20  	"path/filepath"
    21  	"runtime"
    22  	"strconv"
    23  	"testing"
    24  	"time"
    25  )
    26  
    27  // Retry runs function f for up to maxAttempts times until f returns successfully, and reports whether f was run successfully.
    28  // It will sleep for the given period between invocations of f.
    29  // Use the provided *testutil.R instead of a *testing.T from the function.
    30  func Retry(t *testing.T, maxAttempts int, sleep time.Duration, f func(r *R)) bool {
    31  	for attempt := 1; attempt <= maxAttempts; attempt++ {
    32  		r := &R{Attempt: attempt, log: &bytes.Buffer{}}
    33  
    34  		f(r)
    35  
    36  		if !r.failed {
    37  			if r.log.Len() != 0 {
    38  				t.Logf("Success after %d attempts:%s", attempt, r.log.String())
    39  			}
    40  			return true
    41  		}
    42  
    43  		if attempt == maxAttempts {
    44  			t.Logf("FAILED after %d attempts:%s", attempt, r.log.String())
    45  			t.Fail()
    46  		}
    47  
    48  		time.Sleep(sleep)
    49  	}
    50  	return false
    51  }
    52  
    53  // RetryWithoutTest is a variant of Retry that does not use a testing parameter.
    54  // It is meant for testing utilities that do not pass around the testing context, such as cloudrunci.
    55  func RetryWithoutTest(maxAttempts int, sleep time.Duration, f func(r *R)) bool {
    56  	for attempt := 1; attempt <= maxAttempts; attempt++ {
    57  		r := &R{Attempt: attempt, log: &bytes.Buffer{}}
    58  
    59  		f(r)
    60  
    61  		if !r.failed {
    62  			if r.log.Len() != 0 {
    63  				r.Logf("Success after %d attempts:%s", attempt, r.log.String())
    64  			}
    65  			return true
    66  		}
    67  
    68  		if attempt == maxAttempts {
    69  			r.Logf("FAILED after %d attempts:%s", attempt, r.log.String())
    70  			return false
    71  		}
    72  
    73  		time.Sleep(sleep)
    74  	}
    75  	return false
    76  }
    77  
    78  // R is passed to each run of a flaky test run, manages state and accumulates log statements.
    79  type R struct {
    80  	// The number of current attempt.
    81  	Attempt int
    82  
    83  	failed bool
    84  	log    *bytes.Buffer
    85  }
    86  
    87  // Fail marks the run as failed, and will retry once the function returns.
    88  func (r *R) Fail() {
    89  	r.failed = true
    90  }
    91  
    92  // Errorf is equivalent to Logf followed by Fail.
    93  func (r *R) Errorf(s string, v ...interface{}) {
    94  	r.logf(s, v...)
    95  	r.Fail()
    96  }
    97  
    98  // Logf formats its arguments and records it in the error log.
    99  // The text is only printed for the final unsuccessful run or the first successful run.
   100  func (r *R) Logf(s string, v ...interface{}) {
   101  	r.logf(s, v...)
   102  }
   103  
   104  func (r *R) logf(s string, v ...interface{}) {
   105  	fmt.Fprint(r.log, "\n")
   106  	fmt.Fprint(r.log, lineNumber())
   107  	fmt.Fprintf(r.log, s, v...)
   108  }
   109  
   110  func lineNumber() string {
   111  	_, file, line, ok := runtime.Caller(3) // logf, public func, user function
   112  	if !ok {
   113  		return ""
   114  	}
   115  	return filepath.Base(file) + ":" + strconv.Itoa(line) + ": "
   116  }
   117
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