Add a test to prove the Tracer is safe for concurrent calls (#1665)

* Add test to prove the Tracer is safe for concurrent calls

* Fix NotToPanic of harness never call the input func

* Fix tests

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>

internal/matchers/expectation.go

@@ -84,8 +84,19 @@ func (e *Expectation) ToBeFalse() {
 }
 
 func (e *Expectation) NotToPanic() {
-	if actual := recover(); actual != nil {
-		e.fail(fmt.Sprintf("Expected panic\n\t%v\nto have not been raised", actual))
+	switch a := e.actual.(type) {
+	case func():
+		func() {
+			defer func() {
+				if recovered := recover(); recovered != nil {
+					e.fail(fmt.Sprintf("Expected panic\n\t%v\nto have not been raised", recovered))
+				}
+			}()
+
+			a()
+		}()
+	default:
+		e.fail(fmt.Sprintf("Cannot check if non-func value\n\t%v\nis truthy", a))
 	}
 }
 

internal/tools/tools.go

@@ -18,8 +18,8 @@ package tools
 
 import (
 	_ "github.com/client9/misspell/cmd/misspell"
+	_ "github.com/gogo/protobuf/protoc-gen-gogofast"
 	_ "github.com/golangci/golangci-lint/cmd/golangci-lint"
 	_ "github.com/itchyny/gojq"
 	_ "golang.org/x/tools/cmd/stringer"
-	_ "github.com/gogo/protobuf/protoc-gen-gogofast"
 )

oteltest/harness.go

@@ -217,6 +217,44 @@ func (h *Harness) TestTracer(subjectFactory func() trace.Tracer) {
 			e.Expect(csc.TraceID()).NotToEqual(psc.TraceID())
 			e.Expect(csc.SpanID()).NotToEqual(psc.SpanID())
 		})
+
+		t.Run("all methods are safe to be called concurrently", func(t *testing.T) {
+			t.Parallel()
+
+			e := matchers.NewExpecter(t)
+			tracer := subjectFactory()
+
+			ctx, parent := tracer.Start(context.Background(), "span")
+
+			runner := func(tp trace.Tracer) <-chan struct{} {
+				done := make(chan struct{})
+				go func(tp trace.Tracer) {
+					var wg sync.WaitGroup
+					for i := 0; i < 20; i++ {
+						wg.Add(1)
+						go func(name string) {
+							defer wg.Done()
+							_, child := tp.Start(ctx, name)
+
+							psc := parent.SpanContext()
+							csc := child.SpanContext()
+
+							e.Expect(csc.TraceID()).ToEqual(psc.TraceID())
+							e.Expect(csc.SpanID()).NotToEqual(psc.SpanID())
+						}(fmt.Sprintf("span %d", i))
+					}
+					wg.Wait()
+					done <- struct{}{}
+				}(tp)
+				return done
+			}
+
+			e.Expect(func() {
+				done := runner(tracer)
+
+				<-done
+			}).NotToPanic()
+		})
 	})
 
 	h.testSpan(subjectFactory)