pulumi/sdk/go/common/promise/promise_test.go

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Add a strict opinionated promise library (#14552) <!--- Thanks so much for your contribution! If this is your first time contributing, please ensure that you have read the [CONTRIBUTING](https://github.com/pulumi/pulumi/blob/master/CONTRIBUTING.md) documentation. --> # Description <!--- Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. --> Prompted by having another case in https://github.com/pulumi/pulumi/pull/14548 that looked like "this is just a promise". We already had a mini-promise library for provider config in sdk/go/common/resource/plugin/provider_plugin.go. Plus a couple of places where we did a poor mans Go promise by having a WaitGroup plus a variable to set (see the two changes in /pkg). This adds a little promise library to safely cover all three of these cases plus the case I'll be adding in #14548. It is _minimal_ adding just the features of promises needed for these initial cases. We can add to it as needed. I suspect we've got a number of places in test code that could probably use this as well, but I haven't gone through that. I also suspect that having this type available will result in more places in the future being simpler because "its just a promise" is a fairly common scenario in async systems. In fact Output's internally _are just a promise_ so we could probably rewrite their internals using this, add a `Then()` like method for apply and all the async complexity gets handled in the promise layer while the output layer just cares about unknowns/secrets/etc. ## Checklist - [x] I have run `make tidy` to update any new dependencies - [x] I have run `make lint` to verify my code passes the lint check - [ ] I have formatted my code using `gofumpt` <!--- Please provide details if the checkbox below is to be left unchecked. --> - [x] I have added tests that prove my fix is effective or that my feature works <!--- User-facing changes require a CHANGELOG entry. --> - [ ] I have run `make changelog` and committed the `changelog/pending/<file>` documenting my change - This is in sdk/go/common and I'm considering it an non-public api for now. <!-- If the change(s) in this PR is a modification of an existing call to the Pulumi Cloud, then the service should honor older versions of the CLI where this change would not exist. You must then bump the API version in /pkg/backend/httpstate/client/api.go, as well as add it to the service. --> - [ ] Yes, there are changes in this PR that warrants bumping the Pulumi Cloud API version <!-- @Pulumi employees: If yes, you must submit corresponding changes in the service repo. -->
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// Copyright 2016-2023, Pulumi Corporation.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package promise
import (
"context"
"errors"
"sync"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestZeroPanic(t *testing.T) {
t.Parallel()
var p Promise[int]
assert.PanicsWithValue(t, "Promise must be initialized", func() {
p.Result(context.Background()) //nolint:errcheck // Result is expected to panic
})
}
func TestFulfill(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
set := ps.Fulfill(42)
assert.True(t, set, "set should be true")
promise := ps.Promise()
i, err := promise.Result(context.Background())
require.NoError(t, err)
assert.Equal(t, 42, i)
// Trying to fulfill again should fail
set = ps.Fulfill(43)
assert.False(t, set, "set should be false")
// Asking for the promise again should give the same promise
assert.Equal(t, promise, ps.Promise())
// Result should still be 42
i, err = promise.Result(context.Background())
require.NoError(t, err)
assert.Equal(t, 42, i)
// Trying to reject should fail
set = ps.Reject(errors.New("boom"))
assert.False(t, set, "set should be false")
}
func TestMustFulfill(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
// First call should succeed
ps.MustFulfill(42)
// And this promise should now resolve to 42
i, err := ps.Promise().Result(context.Background())
require.NoError(t, err)
assert.Equal(t, 42, i)
// Second call should panic
assert.PanicsWithValue(t, "CompletionSource already resolved", func() {
ps.MustFulfill(43)
})
}
func TestReject(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
boom := errors.New("boom")
set := ps.Reject(boom)
assert.True(t, set, "set should be true")
promise := ps.Promise()
_, err := promise.Result(context.Background())
require.Equal(t, boom, err)
// Trying to reject again should fail
set = ps.Reject(errors.New("bigger boom"))
assert.False(t, set, "set should be false")
// Asking for the promise again should give the same promise
assert.Equal(t, promise, ps.Promise())
// Result should still be boom
promise = ps.Promise()
_, err = promise.Result(context.Background())
require.Equal(t, boom, err)
// Trying to fulfill should fail
set = ps.Fulfill(42)
assert.False(t, set, "set should be false")
}
func TestMustReject(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
// First call should succeed
boom := errors.New("boom")
ps.MustReject(boom)
// And this promise should now resolve to boom
_, err := ps.Promise().Result(context.Background())
require.Equal(t, boom, err)
// Second call should panic
assert.PanicsWithValue(t, "CompletionSource already resolved", func() {
ps.MustReject(errors.New("boom again"))
})
}
func TestManyGets(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
ctx := context.Background()
var wg sync.WaitGroup
for i := 0; i < 10; i++ {
wg.Add(1)
go func() {
defer wg.Done()
got, err := ps.Promise().Result(ctx)
assert.NoError(t, err)
assert.Equal(t, 42, got)
}()
}
ps.Fulfill(42)
wg.Wait()
}
func TestAwaitCancelled(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
ps := &CompletionSource[int]{}
p := ps.Promise()
done := make(chan struct{})
go func() {
defer close(done)
_, err := p.Result(ctx)
assert.ErrorIs(t, err, context.Canceled)
}()
cancel()
<-done
// The await was cancelled, not the promise so we should be able to fulfill and then wait again.
set := ps.Fulfill(12)
assert.True(t, set, "set should be true")
i, err := p.Result(context.Background())
require.NoError(t, err)
assert.Equal(t, 12, i)
}
Use promise rather than `atomic.Value` to record step errors. (#14612) <!--- Thanks so much for your contribution! If this is your first time contributing, please ensure that you have read the [CONTRIBUTING](https://github.com/pulumi/pulumi/blob/master/CONTRIBUTING.md) documentation. --> # Description <!--- Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. --> Fixes https://github.com/pulumi/pulumi/issues/14611. `atomic.Value` panics if a second value is written to it which isn't _exactly_ the same type. We were using this to atomically record any errors that happened, although where only interested in saving the first error. This was fine if no or one error happened, or if multiple errors happened that all were the same error type. But if two errors if different error types happened `sync.Value` would panic. Switched to use a promise completion source instead. If any error happens we use it to reject the completion source, we also log if this isn't the first error we've seen (a capabilitiy that `sync.Value` didn't give us). At the end of the step executor being used when `Errored()` is called we try to get the result of the completion source. ## Checklist - [x] I have run `make tidy` to update any new dependencies - [x] I have run `make lint` to verify my code passes the lint check - [ ] I have formatted my code using `gofumpt` <!--- Please provide details if the checkbox below is to be left unchecked. --> - [x] I have added tests that prove my fix is effective or that my feature works - Added tests for the new promise function `TryResult`, not sure it's that needed to try and write a test for the error case we hit in #14611 now that it's type safe. <!--- User-facing changes require a CHANGELOG entry. --> - [x] I have run `make changelog` and committed the `changelog/pending/<file>` documenting my change <!-- If the change(s) in this PR is a modification of an existing call to the Pulumi Cloud, then the service should honor older versions of the CLI where this change would not exist. You must then bump the API version in /pkg/backend/httpstate/client/api.go, as well as add it to the service. --> - [ ] Yes, there are changes in this PR that warrants bumping the Pulumi Cloud API version <!-- @Pulumi employees: If yes, you must submit corresponding changes in the service repo. -->
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func TestTryResult(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
p := ps.Promise()
// TryResult should return false if the promise is not yet resolved.
_, _, ok := p.TryResult()
assert.False(t, ok)
// Fulfilling the promise should return true.
set := ps.Fulfill(42)
assert.True(t, set, "set should be true")
// TryResult should now return true and the result.
i, err, ok := p.TryResult()
assert.True(t, ok)
assert.NoError(t, err)
assert.Equal(t, 42, i)
}
func TestTryResultRace(t *testing.T) {
t.Parallel()
ps := &CompletionSource[int]{}
p := ps.Promise()
// Start a promise that will keep trying to get the result of p.
result := Run(func() (int, error) {
for {
i, err, ok := p.TryResult()
if ok {
return i, err
}
}
})
// Set the result of p, setting should return true.
go func() {
set := ps.Fulfill(42)
assert.True(t, set, "set should be true")
}()
// Wait for the result promise.
i, err := result.Result(context.Background())
assert.NoError(t, err)
assert.Equal(t, 42, i)
}