kubernetes/test/utils/ktesting/withcontext.go
Patrick Ohly 551cf6f171 ktesting: reimplement without interface
The original implementation was inspired by how context.Context is handled via
wrapping a parent context. That approach had several issues:

- It is useful to let users call methods (e.g. tCtx.ExpectNoError)
  instead of ktesting functions with a tCtx parameters, but that only
  worked if all implementations of the interface implemented that
  set of methods. This made extending those methods cumbersome (see
  the commit which added Require+Assert) and could potentially break
  implementations of the interface elsewhere, defeating part of the
  motivation for having the interface in the first place.

- It was hard to see how the different TContext wrappers cooperated
  with each other.

- Layering injection of "ERROR" and "FATAL ERROR" on top of prefixing
  with the klog header caused post-processing of a failed unit test to
  remove that line because it looked like log output. Other log output
  lines where kept because they were not indented.

- In Go <=1.25, the `go vet sprintf` check only works for functions and
  methods if they get called directly and themselves directly pass their
  parameters on to fmt.Sprint. The check does not work when calling
  methods through an interface. Support for that is coming in Go 1.26,
  but will depend on bumping the Go version also in go.mod and thus
  may not be immediately possible in Kubernetes.

- Interface documentation in
  https://pkg.go.dev/k8s.io/kubernetes@v1.34.2/test/utils/ktesting#TContext
  is a monolithic text block. Documentation for methods is more readable and allows
  referencing those methods with [] (e.g. [TC.Errorf] works, [TContext.Errorf]
  didn't).

The revised implementation is a single struct with (almost) no exported
fields. The two exceptions (embedded context.Context and TB) are useful because
it avoids having to write wrappers for several functions resp. necessary
because Helper cannot be wrapped. Like a logr.LogSink, With* methods can make a
shallow copy and then change some fields in the cloned instance.

The former `ktesting.TContext` interface is now a type alias for
`*ktesting.TC`. This ensures that existing code using ktesting doesn't need to
be updated and because that code is a bit more compact (`tCtx
ktesting.TContext` instead of `tCtx *ktesting.TContext` when not using such an
alias). Hiding that it is a pointer might discourage accessing the exported
fields because it looks like an interface.

Output gets fixed and improved such that:
- "FATAL ERROR" and "ERROR" are at the start of the line, followed by the klog header.
- The failure message follows in the next line.
- Continuation lines are always indented.

The set of methods exposed via TB is now a bit more complete (Attr, Chdir).

All former stand-alone With* functions are now also available as methods and
should be used instead of the functions. Those will be removed.

Linting of log calls now works and found some issues.
2026-01-05 13:45:03 +01:00

93 lines
2.6 KiB
Go

/*
Copyright 2023 The Kubernetes Authors.
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 ktesting
import (
"context"
"time"
"k8s.io/klog/v2"
)
// Deprecated: use tCtx.WithCancel instead
func WithCancel(tCtx TContext) TContext { return tCtx.WithCancel() }
// WithCancel sets up cancellation in a [TContext.Cleanup] callback and
// constructs a new TContext where [TContext.Cancel] cancels only the new
// context.
func (tc *TC) WithCancel() TContext {
ctx, cancel := context.WithCancelCause(tc)
tc = tc.clone()
tc.Context = ctx
tc.cancel = func(cause string) {
var cancelCause error
if cause != "" {
cancelCause = canceledError(cause)
}
cancel(cancelCause)
}
return tc
}
// Deprecated: use tCtx.WithoutCancel instead
func WithoutCancel(tCtx TContext) TContext { return tCtx.WithoutCancel() }
// WithoutCancel causes the returned context to ignore cancellation of its parent.
// Calling Cancel will not cancel the parent either.
// This matches [context.WithoutCancel].
func (tc *TC) WithoutCancel() TContext {
ctx := context.WithoutCancel(tc)
tc = tc.clone()
tc.Context = ctx
tc.cancel = nil
return tc
}
// Deprecated: use tCtx.WithTimeout instead
func WithTimeout(tCtx TContext, timeout time.Duration, timeoutCause string) TContext {
return tCtx.WithTimeout(timeout, timeoutCause)
}
// WithTimeout sets up new context with a timeout. Canceling the timeout gets
// registered in a cleanup callback. [TContext.Cancel] cancels only
// the new context. The cause is used as reason why the context is canceled
// once the timeout is reached. It may be empty, in which case the usual
// "context canceled" error is used.
func (tc *TC) WithTimeout(timeout time.Duration, timeoutCause string) TContext {
ctx, cancel := withTimeout(tc, tc.TB(), timeout, timeoutCause)
tc = tc.clone()
tc.Context = ctx
tc.cancel = cancel
return tc
}
// Deprecated: used tCtx.WithLogger instead
func WithLogger(tCtx TContext, logger klog.Logger) TContext {
return tCtx.WithLogger(logger)
}
// WithLogger constructs a new context with a different logger.
func (tc *TC) WithLogger(logger klog.Logger) TContext {
ctx := klog.NewContext(tc, logger)
tc = tc.clone()
tc.Context = ctx
return tc
}