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Fix falky file watcher test
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The test method `waitForRead` was sometimes signaling due to accumulated
reads, even it was inteded to wait for a read after a new content was
set in the mock file.

This fixes it by waiting to singal read happened when the read content
is the same as the expected one.
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@sergicastro
sergicastro committed May 14, 2024
1 parent f2ef0e4 commit f2c27ca
Showing 1 changed file with 34 additions and 27 deletions.
61 changes: 34 additions & 27 deletions internal/file_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -50,9 +50,9 @@ func TestFileWatcher_WatchFile(t *testing.T) {
fileReader: newMockReader("test", "original", nil),
genUpdates: func(reader *mockReader) {
reader.setData([]byte("update 1"))
reader.waitForRead()
reader.waitForRead([]byte("update 1"))
reader.setData([]byte("update 2"))
reader.waitForRead()
reader.waitForRead([]byte("update 2"))
},
interval: watcherInterval,
wantCallbacks: 2,
Expand All @@ -64,13 +64,13 @@ func TestFileWatcher_WatchFile(t *testing.T) {
fileReader: newMockReader("test", "original", nil),
genUpdates: func(reader *mockReader) {
reader.setData([]byte("update 1"))
reader.waitForRead()
reader.waitForRead([]byte("update 1"))
reader.setData([]byte("update 2"))
reader.waitForRead()
reader.waitForRead([]byte("update 2"))
reader.setData([]byte("update 2"))
reader.waitForRead()
reader.waitForRead([]byte("update 2"))
reader.setData([]byte("update 2"))
reader.waitForRead()
reader.waitForRead([]byte("update 2"))
},
interval: watcherInterval,
wantCallbacks: 2,
Expand All @@ -85,7 +85,7 @@ func TestFileWatcher_WatchFile(t *testing.T) {
// no waiting for the read to happen and performing next update
// reader.waitForRead()
reader.setData([]byte("update 2"))
reader.waitForRead()
reader.waitForRead([]byte("update 2"))
},
interval: watcherInterval,
wantCallbacks: 1,
Expand All @@ -103,14 +103,14 @@ func TestFileWatcher_WatchFile(t *testing.T) {
fileReader: newMockReader("test", "original", nil),
genUpdates: func(reader *mockReader) {
reader.setData([]byte("update 1"))
reader.waitForRead()
reader.waitForRead([]byte("update 1"))
reader.setErr(errors.New("error reading file"))
reader.waitForRead()
reader.waitForRead([]byte("update 1"))
// stop error
reader.setErr(nil)
// even if an error happens, next updates should be notified
reader.setData([]byte("update 2"))
reader.waitForRead()
reader.waitForRead([]byte("update 2"))
},
interval: watcherInterval,
wantCallbacks: 2,
Expand Down Expand Up @@ -158,7 +158,7 @@ func TestFileWatcher_WatchFile(t *testing.T) {
require.False(t, ok)
}

tt.fileReader.waitForRead() // Wait for the first read to happen, the one synchronous
tt.fileReader.waitForRead(got) // Wait for the first read to happen, the one synchronous
require.Equal(t, tt.want, string(got))
require.NoError(t, err)

Expand Down Expand Up @@ -199,7 +199,7 @@ func TestFileWatcher_WatchFile(t *testing.T) {
mu1.Unlock()
})
require.NoError(t, err)
file1.waitForRead() // Wait for the first read to happen
file1.waitForRead([]byte("original1")) // Wait for the first read to happen

file2 := newMockReader("test2", "original2", nil)
got2, err := fw.WatchFile(file2, watcherInterval, func(data []byte) {
Expand All @@ -209,14 +209,14 @@ func TestFileWatcher_WatchFile(t *testing.T) {
mu2.Unlock()
})
require.NoError(t, err)
file2.waitForRead() // Wait for the first read to happen
file2.waitForRead([]byte("original2")) // Wait for the first read to happen

file1.setData([]byte("update 1-1"))
file1.waitForRead()
file1.waitForRead([]byte("update 1-1"))
file2.setData([]byte("update 2-1"))
file2.waitForRead()
file2.waitForRead([]byte("update 2-1"))
file1.setData([]byte("update 1-2"))
file1.waitForRead()
file1.waitForRead([]byte("update 1-2"))

// ensure no more updates are notified before verifying the results
cancel()
Expand Down Expand Up @@ -250,7 +250,7 @@ func TestFileWatcher_WatchFile(t *testing.T) {
muU.Unlock()
})
require.NoError(t, err)
file1.waitForRead() // Wait for the first read to happen
file1.waitForRead([]byte("original")) // Wait for the first read to happen

wg := sync.WaitGroup{}
wg.Add(2) // 2 callbacks to be notified
Expand All @@ -263,12 +263,12 @@ func TestFileWatcher_WatchFile(t *testing.T) {
muO.Unlock()
})
require.NoError(t, err)
file1.waitForRead() // Wait for the first read to happen again
file1.waitForRead([]byte("override")) // Wait for the first read to happen again

file1.setData([]byte("update 1"))
file1.waitForRead()
file1.waitForRead([]byte("update 1"))
file1.setData([]byte("update 2"))
file1.waitForRead()
file1.waitForRead([]byte("update 2"))

// ensure no more updates are notified before verifying the results
cancel()
Expand All @@ -293,15 +293,15 @@ type mockReader struct {

// reads is used to signal that a read happened, it should be buffered to avoid deadlocks.
// It is used to know if a read happened but there's no need to block reads happening if no one is waiting for them.
reads chan struct{}
reads chan []byte
}

func newMockReader(id, data string, err error) *mockReader {
return &mockReader{
id: id,
fileData: []byte(data),
err: err,
reads: make(chan struct{}, 50),
reads: make(chan []byte, 50),
}
}

Expand All @@ -310,12 +310,12 @@ func (m *mockReader) ID() string {
}

func (m *mockReader) Read() ([]byte, error) {
// Notify that a read happened
defer func() { m.reads <- struct{}{} }()

m.m.Lock()
defer m.m.Unlock()

// Notify that a read happened
defer func() { m.reads <- m.fileData }()

if m.err != nil {
return nil, m.err
}
Expand All @@ -335,6 +335,13 @@ func (m *mockReader) setErr(err error) {
m.err = err
}

func (m *mockReader) waitForRead() {
<-m.reads
// waitForRead blocks until the file data is the same as the expected.
// So it ensures that when it is invoked after setData, it will wait for this same
// data to be returned by the Read method.
func (m *mockReader) waitForRead(expected []byte) {
readData := <-m.reads // wait for at least first read
// then if the read data is not the same as the expected data, wait for the next read
for string(readData) != string(expected) {
readData = <-m.reads
}
}

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