go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue TestLastValueMerge failure

[MrAlias]

Running the test suite on Windows amd64 for both Go 1.15 and 1.14:

--- FAIL: TestLastValueMerge (0.00s)
    --- FAIL: TestLastValueMerge/Int64Kind (0.00s)
        lastvalue_test.go:116: 
            	Error Trace:	lastvalue_test.go:116
            	            				test.go:75
            	Error:      	Should be true
            	Test:       	TestLastValueMerge/Int64Kind
    --- FAIL: TestLastValueMerge/Float64Kind (0.00s)
        lastvalue_test.go:116: 
            	Error Trace:	lastvalue_test.go:116
            	            				test.go:75
            	Error:      	Should be true
            	Test:       	TestLastValueMerge/Float64Kind
FAIL
FAIL	go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue	0.030s

Looking at the code

opentelemetry-go/sdk/metric/aggregator/lastvalue/lastvalue_test.go

Lines 93 to 125 in 4a163be

	func TestLastValueMerge(t *testing.T) {
	aggregatortest.RunProfiles(t, func(t *testing.T, profile aggregatortest.Profile) {
	agg1, agg2, ckpt1, ckpt2 := new4()
	descriptor := aggregatortest.NewAggregatorTest(metric.ValueObserverInstrumentKind, profile.NumberKind)
	first1 := profile.Random(+1)
	first2 := profile.Random(+1)
	first1.AddNumber(profile.NumberKind, first2)
	aggregatortest.CheckedUpdate(t, agg1, first1, descriptor)
	aggregatortest.CheckedUpdate(t, agg2, first2, descriptor)
	require.NoError(t, agg1.SynchronizedMove(ckpt1, descriptor))
	require.NoError(t, agg2.SynchronizedMove(ckpt2, descriptor))
	checkZero(t, agg1)
	checkZero(t, agg2)
	_, t1, err := ckpt1.LastValue()
	require.Nil(t, err)
	_, t2, err := ckpt2.LastValue()
	require.Nil(t, err)
	require.True(t, t1.Before(t2))
	aggregatortest.CheckedMerge(t, ckpt1, ckpt2, descriptor)
	lv, ts, err := ckpt1.LastValue()
	require.Nil(t, err)
	require.Equal(t, t2, ts, "Merged timestamp - non-monotonic")
	require.Equal(t, first2, lv, "Merged value - non-monotonic")
	})
	}

Again this looks like we need to add an artificial delay to ensure the checkpoint doesn't happen with the same timestamp.