open-match.dev/open-match@v1.8.1/examples/demo/bytesub/bytesub_test.go (about)

     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  //     http://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 bytesub provides the ability for many clients to subscribe to the
    16  // latest value of a byte array.
    17  package bytesub
    18  
    19  import (
    20  	"context"
    21  	"errors"
    22  	"testing"
    23  )
    24  
    25  // TestFastAndSlow ensures that if a slow subscriber is blocked, faster subscribers
    26  // nor publishers aren't blocked.  It also ensures that values published while slow
    27  // wasn't listening are skipped.
    28  func TestFastAndSlow(t *testing.T) {
    29  	ctx, cancel := context.WithCancel(context.Background())
    30  	fast := make(chan string)
    31  	slow := make(chan string)
    32  
    33  	s := New()
    34  
    35  	go func() {
    36  		s.Subscribe(ctx, chanWriter{fast})
    37  		close(fast)
    38  	}()
    39  	go func() {
    40  		s.Subscribe(ctx, chanWriter{slow})
    41  		close(slow)
    42  	}()
    43  
    44  	for _, i := range []string{"0", "1", "2", "3"} {
    45  		s.AnnounceLatest([]byte(i))
    46  		if v := <-fast; v != i {
    47  			t.Errorf("Expected \"%s\", got \"%s\"", i, v)
    48  		}
    49  	}
    50  
    51  	for count := 0; true; count++ {
    52  		if v := <-slow; v == "3" {
    53  			if count > 1 {
    54  				t.Error("Expected to receive at most 1 other value on slow before receiving the latest value.")
    55  			}
    56  			break
    57  		}
    58  	}
    59  
    60  	cancel()
    61  	_, ok := <-fast
    62  	if ok {
    63  		t.Error("Expected subscribe to return and fast to be closed")
    64  	}
    65  	_, ok = <-slow
    66  	if ok {
    67  		t.Error("Expected subscribe to return and slow to be closed")
    68  	}
    69  }
    70  
    71  func TestBadWriter(t *testing.T) {
    72  	ctx, cancel := context.WithCancel(context.Background())
    73  	defer cancel()
    74  
    75  	s := New()
    76  	s.AnnounceLatest([]byte{0, 1, 2})
    77  	err := s.Subscribe(ctx, writerFunc(func(b []byte) (int, error) {
    78  		return 1, nil
    79  	}))
    80  
    81  	if err != partialWriteError {
    82  		t.Errorf("Expected partialWriteError, got %s", err)
    83  	}
    84  }
    85  
    86  func TestErrorReturned(t *testing.T) {
    87  	ctx, cancel := context.WithCancel(context.Background())
    88  	defer cancel()
    89  
    90  	expected := errors.New("Hello there.")
    91  
    92  	s := New()
    93  	s.AnnounceLatest([]byte{0, 1, 2})
    94  	err := s.Subscribe(ctx, writerFunc(func(b []byte) (int, error) {
    95  		return 0, expected
    96  	}))
    97  
    98  	if err != expected {
    99  		t.Errorf("Expected returned error, got %s", err)
   100  	}
   101  }
   102  
   103  func TestContextError(t *testing.T) {
   104  	ctx, cancel := context.WithCancel(context.Background())
   105  	cancel()
   106  
   107  	s := New()
   108  	s.AnnounceLatest([]byte{0, 1, 2})
   109  	err := s.Subscribe(ctx, writerFunc(func(b []byte) (int, error) {
   110  		return len(b), nil
   111  	}))
   112  
   113  	if err != context.Canceled {
   114  		t.Errorf("Expected context canceled error, got %s", err)
   115  	}
   116  }
   117  
   118  type chanWriter struct {
   119  	c chan string
   120  }
   121  
   122  func (cw chanWriter) Write(b []byte) (int, error) {
   123  	cw.c <- string(b)
   124  	return len(b), nil
   125  }
   126  
   127  type writerFunc func(b []byte) (int, error)
   128  
   129  func (w writerFunc) Write(b []byte) (int, error) {
   130  	return w(b)
   131  }