Flaky test: TestWait

[MrAlias]

Description

https://github.com/open-telemetry/opentelemetry-go/runs/3931346951?check_suite_focus=true

2021-10-18T20:06:05.5955681Z --- FAIL: TestWait (0.00s)
2021-10-18T20:06:05.5956675Z     retry_test.go:58: 
2021-10-18T20:06:05.5957379Z         	Error Trace:	retry_test.go:58
2021-10-18T20:06:05.5958052Z         	Error:      	Not equal: 
2021-10-18T20:06:05.5959213Z         	            	expected: *errors.errorString(&errors.errorString{s:"context canceled"})
2021-10-18T20:06:05.5960528Z         	            	actual  : <nil>(<nil>)
2021-10-18T20:06:05.5961187Z         	Test:       	TestWait
2021-10-18T20:06:05.5961735Z FAIL
2021-10-18T20:06:05.5963051Z FAIL	go.opentelemetry.io/otel/exporters/otlp/otlptrace/internal/retry	0.034s
2021-10-18T20:06:06.1576065Z ok  	go.opentelemetry.io/otel/exporters/otlp/otlptrace/internal/tracetransform	0.032s
2021-10-18T20:06:06.1577837Z FAIL
2021-10-18T20:06:06.3127156Z mingw32-make: *** [Makefile:113: test] Error 123
2021-10-18T20:06:06.7569802Z ##[error]Process completed with exit code 1.

opentelemetry-go/exporters/otlp/otlptrace/internal/retry/retry_test.go

Lines 48 to 53 in 69b88ab

	ctx: func() context.Context {
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	return ctx
	}(),
	expected: context.Canceled,

Environment

• OS: Microsoft Windows Server 2019 10.0.17763
• Architecture: amd64
• Go Version: 1.16
• opentelemetry-go version: 69b88ab

log.txt

[MrAlias]

This looks similar to #2289

This select statement will randomly return different errors when both cases are simultaneously satisfied.

opentelemetry-go/exporters/otlp/otlptrace/internal/retry/retry.go

Lines 123 to 127 in 69b88ab

	select {
	case <-ctx.Done():
	return ctx.Err()
	case <-timer.C:
	}

[MrAlias]

I'm able to reproduce this failure locally.

$ go test -run=TestWait -count 1000000 -failfast ./...
--- FAIL: TestWait (0.00s)
    retry_test.go:58:
        	Error Trace:	retry_test.go:58
        	Error:      	Not equal:
        	            	expected: *errors.errorString(&errors.errorString{s:"context canceled"})
        	            	actual  : <nil>(<nil>)
        	Test:       	TestWait
FAIL
FAIL	go.opentelemetry.io/otel/exporters/otlp/otlptrace/internal/retry	0.005s
FAIL