feat(trace): Added possibility to dump spans from test processor (#96)

Author: ekkinox

docs/modules/fxtrace.md

@@ -99,6 +99,8 @@ You can use the provided [test assertion helpers](https://github.com/ankorstore/
 - `AssertContainTraceSpan`: to assert on exact name and partial attributes match
 - `AssertContainNotTraceSpan`: to assert on exact name and partial attributes non match
 
+and use `Dump()` to print the current content of the [TestTraceExporter](https://github.com/ankorstore/yokai/blob/main/trace/tracetest/exporter.go).
+
 For example:
 
 ```go title="internal/example_test.go"
@@ -130,6 +132,9 @@ func TestExample(t *testing.T) {
 			defer span.End()
 		}),
 	)
+	
+	//dump spans
+	traceExporter.Dump()
 
 	// trace assertion example
 	tracetest.AssertHasTraceSpan(

trace/README.md

@@ -200,6 +200,8 @@ You can use the provided [test assertion helpers](tracetest/assert.go) in your t
 - `AssertContainTraceSpan`: to assert on exact name and partial attributes match
 - `AssertContainNotTraceSpan`: to assert on exact name and partial attributes non match
 
+and use `Dump()` to print the current content of the test span processor.
+
 ```go
 package main_test
 
@@ -227,6 +229,9 @@ func TestTracer(t *testing.T) {
 		attribute.Int("int attr name", 42),
 	)
 	span.End()
+	
+	// dump spans
+	ex.Dump()
 
 	// assertion success
 	tracetest.AssertHasTraceSpan(

trace/tracetest/exporter.go

@@ -18,6 +18,7 @@ type TestTraceExporter interface {
 	Span(name string) (tracetest.SpanStub, error)
 	HasSpan(expectedName string, expectedAttributes ...attribute.KeyValue) bool
 	ContainSpan(expectedName string, expectedAttributes ...attribute.KeyValue) bool
+	Dump()
 }
 
 // DefaultTestTraceExporter is the default [TestTraceExporter] implementation.
@@ -137,3 +138,11 @@ func (e *DefaultTestTraceExporter) ContainSpan(expectedName string, expectedAttr
 
 	return false
 }
+
+// Dump prints the [tracetest.SpanStubs] snapshots from the in memory internal exporter, for debugging purposes.
+func (e *DefaultTestTraceExporter) Dump() {
+	for _, span := range e.Spans().Snapshots() {
+		//nolint:forbidigo
+		fmt.Printf("%v\n", span)
+	}
+}

trace/tracetest/exporter_test.go

@@ -2,6 +2,8 @@ package tracetest_test
 
 import (
 	"context"
+	"io"
+	"os"
 	"testing"
 
 	"github.com/ankorstore/yokai/trace"
@@ -312,3 +314,46 @@ func TestContainSpan(t *testing.T) {
 		),
 	)
 }
+
+func TestDump(t *testing.T) {
+	t.Parallel()
+
+	exporter := tracetest.NewDefaultTestTraceExporter()
+
+	tracerProvider, err := trace.NewDefaultTracerProviderFactory().Create(
+		trace.WithSpanProcessor(trace.NewTestSpanProcessor(exporter)),
+	)
+	assert.NoError(t, err)
+
+	tracer := tracerProvider.Tracer("test")
+
+	_, span := tracer.Start(
+		context.Background(),
+		"test span",
+		oteltrace.WithAttributes(
+			attribute.String("string attribute name", "string attribute value"),
+			attribute.Int("int attribute name", 42),
+		),
+	)
+	span.End()
+
+	defaultStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	exporter.Dump()
+
+	err = w.Close()
+	assert.NoError(t, err)
+
+	out, err := io.ReadAll(r)
+	assert.NoError(t, err)
+
+	os.Stdout = defaultStdout
+
+	outStr := string(out)
+
+	assert.Contains(t, outStr, "test span")
+	assert.Contains(t, outStr, "string attribute value")
+	assert.Contains(t, outStr, "42")
+}