| 1 | // Copyright 2020 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package eventtest supports logging events to a test. |
| 6 | // You can use NewContext to create a context that knows how to deliver |
| 7 | // telemetry events back to the test. |
| 8 | // You must use this context or a derived one anywhere you want telemetry to be |
| 9 | // correctly routed back to the test it was constructed with. |
| 10 | // Any events delivered to a background context will be dropped. |
| 11 | // |
| 12 | // Importing this package will cause it to register a new global telemetry |
| 13 | // exporter that understands the special contexts returned by NewContext. |
| 14 | // This means you should not import this package if you are not going to call |
| 15 | // NewContext. |
| 16 | package eventtest |
| 17 | |
| 18 | import ( |
| 19 | "bytes" |
| 20 | "context" |
| 21 | "sync" |
| 22 | "testing" |
| 23 | |
| 24 | "golang.org/x/tools/internal/event" |
| 25 | "golang.org/x/tools/internal/event/core" |
| 26 | "golang.org/x/tools/internal/event/export" |
| 27 | "golang.org/x/tools/internal/event/label" |
| 28 | ) |
| 29 | |
| 30 | func init() { |
| 31 | e := &testExporter{buffer: &bytes.Buffer{}} |
| 32 | e.logger = export.LogWriter(e.buffer, false) |
| 33 | |
| 34 | event.SetExporter(export.Spans(e.processEvent)) |
| 35 | } |
| 36 | |
| 37 | type testingKeyType int |
| 38 | |
| 39 | const testingKey = testingKeyType(0) |
| 40 | |
| 41 | // NewContext returns a context you should use for the active test. |
| 42 | func NewContext(ctx context.Context, t testing.TB) context.Context { |
| 43 | return context.WithValue(ctx, testingKey, t) |
| 44 | } |
| 45 | |
| 46 | type testExporter struct { |
| 47 | mu sync.Mutex |
| 48 | buffer *bytes.Buffer |
| 49 | logger event.Exporter |
| 50 | } |
| 51 | |
| 52 | func (w *testExporter) processEvent(ctx context.Context, ev core.Event, tm label.Map) context.Context { |
| 53 | w.mu.Lock() |
| 54 | defer w.mu.Unlock() |
| 55 | // build our log message in buffer |
| 56 | result := w.logger(ctx, ev, tm) |
| 57 | v := ctx.Value(testingKey) |
| 58 | // get the testing.TB |
| 59 | if w.buffer.Len() > 0 && v != nil { |
| 60 | v.(testing.TB).Log(w.buffer) |
| 61 | } |
| 62 | w.buffer.Truncate(0) |
| 63 | return result |
| 64 | } |
| 65 |
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