thetorpedodog commented on a change in pull request #11413: [BEAM-9746] check
for 0 length copies from state
URL: https://github.com/apache/beam/pull/11413#discussion_r408412639
##########
File path: sdks/go/pkg/beam/core/runtime/harness/statemgr_test.go
##########
@@ -258,6 +261,167 @@ func TestStateChannel(t *testing.T) {
}
}
+// TestStateKeyReader validates ordinary Read cases
+func TestStateKeyReader(t *testing.T) {
+ const readLen = 4
+ tests := []struct {
+ name string
+ buflens []int // sizes of the buffers received on the state
channel.
+ numReads int
+ closed bool // tries to read from closed reader
+ noGet bool // tries to read from nil get response reader
+ }{
+ {
+ name: "emptyData",
+ buflens: []int{-1},
+ numReads: 1,
+ }, {
+ name: "singleBufferSingleRead",
+ buflens: []int{readLen},
+ numReads: 2,
+ }, {
+ name: "singleBufferMultipleReads",
+ buflens: []int{2 * readLen},
+ numReads: 3,
+ }, {
+ name: "singleBufferShortRead",
+ buflens: []int{readLen - 1},
+ numReads: 2,
+ }, {
+ name: "multiBuffer",
+ buflens: []int{readLen, readLen},
+ numReads: 3,
+ }, {
+ name: "multiBuffer-short-reads",
+ buflens: []int{readLen - 1, readLen - 1, readLen - 2},
+ numReads: 4,
+ }, {
+ name: "emptyDataFirst", // Shouldn't happen, but
not unreasonable to handle.
+ buflens: []int{-1, readLen, readLen},
+ numReads: 4,
+ }, {
+ name: "emptyDataMid", // Shouldn't happen, but not
unreasonable to handle.
+ buflens: []int{readLen, readLen, -1, readLen},
+ numReads: 5,
+ }, {
+ name: "emptyDataLast", // Shouldn't happen, but not
unreasonable to handle.
+ buflens: []int{readLen, readLen, -1},
+ numReads: 3,
+ }, {
+ name: "emptyDataLast-short",
+ buflens: []int{3*readLen - 2, -1},
+ numReads: 4,
+ }, {
+ name: "closed",
+ buflens: []int{-1, -1},
+ numReads: 1,
+ closed: true,
+ }, {
+ name: "noGet",
+ buflens: []int{-1},
+ numReads: 1,
+ noGet: true,
+ },
+ }
+ for _, test := range tests {
+ t.Run(test.name, func(t *testing.T) {
+ ctx, cancelFn :=
context.WithCancel(context.Background())
+ ch := &StateChannel{
+ id: "test",
+ requests: make(chan *fnpb.StateRequest),
+ responses: make(map[string]chan<-
*fnpb.StateResponse),
+ cancelFn: cancelFn,
+ DoneCh: ctx.Done(),
+ }
+
+ // Handle the channel behavior asynchronously.
+ go func() {
+ for i := 0; i < len(test.buflens); i++ {
+ token := []byte(strconv.Itoa(i))
+ var buf []byte
+ if test.buflens[i] >= 0 {
+ buf = bytes.Repeat([]byte{42},
test.buflens[i])
+ }
+ // On the last request response pair,
send no token.
+ if i+1 == len(test.buflens) {
+ token = nil
+ }
+
+ req := <-ch.requests
+
+ if test.noGet {
+ ch.responses[req.Id] <-
&fnpb.StateResponse{
+ Id: req.Id,
+ }
+ return
+ }
+
+ ch.responses[req.Id] <-
&fnpb.StateResponse{
+ Id: req.Id,
+ Response:
&fnpb.StateResponse_Get{
+ Get:
&fnpb.StateGetResponse{
+
ContinuationToken: token,
+ Data:
buf,
+ },
+ },
+ }
+ }
+ }()
+
+ r := stateKeyReader{
+ ch: ch,
+ }
+
+ if test.closed {
+ err := r.Close()
+ if err != nil {
+ t.Errorf("unexpected error on Close(),
got %v", err)
+ }
+ }
+
+ var totalBytes int
+ for _, l := range test.buflens {
+ if l > 0 {
+ totalBytes += l
+ }
+ }
+ var finalerr error
+ var count, reads int
+
+ // Read all the bytes.
+ for count <= totalBytes {
+ reads++
+ b := make([]byte, readLen) // io.Read is keyed
off of length, not capacity.
+ n, err := r.Read(b)
+ if err != nil {
+ finalerr = err
+ break
+ }
+ count += n
+ // Special check to avoid spurious zero
elements.
+ if count == totalBytes && n == 0 {
+ t.Error("expected byte count read, last
read is 0, but no EOF")
+ }
+ }
+ if got, want := reads, test.numReads; got != want {
Review comment:
Is this a common idiom in beam testing? Inside Google, I don't think I've
seen reassignment to want/got for things which are already stored in their own
variables. I would expect something like:
```go
if reads != test.numReads {
t.Errorf("read %d times, want %d", reads, test.numReads)
}
```
for simpler tests I have seen things like:
```go
if got := sut.CallSomeFn(params); got != tc.want {
// ...
}
```
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