Test the SDK's Span.SpanContext method

Part of #954

sdk/trace_test.go

@@ -4,6 +4,7 @@
 package sdk
 
 import (
+	"context"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -12,18 +13,26 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
-var attrs = []attribute.KeyValue{
-	attribute.Bool("bool", true),
-	attribute.Int("int", -1),
-	attribute.Int64("int64", 43),
-	attribute.Float64("float64", 0.3),
-	attribute.String("string", "value"),
-	attribute.BoolSlice("bool slice", []bool{true, false, true}),
-	attribute.IntSlice("int slice", []int{-1, -30, 328}),
-	attribute.Int64Slice("int64 slice", []int64{1030, 0, 0}),
-	attribute.Float64Slice("float64 slice", []float64{1e9}),
-	attribute.StringSlice("string slice", []string{"one", "two"}),
-}
+var (
+	attrs = []attribute.KeyValue{
+		attribute.Bool("bool", true),
+		attribute.Int("int", -1),
+		attribute.Int64("int64", 43),
+		attribute.Float64("float64", 0.3),
+		attribute.String("string", "value"),
+		attribute.BoolSlice("bool slice", []bool{true, false, true}),
+		attribute.IntSlice("int slice", []int{-1, -30, 328}),
+		attribute.Int64Slice("int64 slice", []int64{1030, 0, 0}),
+		attribute.Float64Slice("float64 slice", []float64{1e9}),
+		attribute.StringSlice("string slice", []string{"one", "two"}),
+	}
+
+	spanContext0 = trace.NewSpanContext(trace.SpanContextConfig{
+		TraceID:    trace.TraceID{0x1},
+		SpanID:     trace.SpanID{0x1},
+		TraceFlags: trace.FlagsSampled,
+	})
+)
 
 func TestSpanNilUnsampledGuards(t *testing.T) {
 	run := func(fn func(s *span)) func(*testing.T) {
@@ -47,3 +56,29 @@ func TestSpanNilUnsampledGuards(t *testing.T) {
 	t.Run("SetAttributes", run(func(s *span) { s.SetAttributes(attrs...) }))
 	t.Run("TracerProvider", run(func(s *span) { _ = s.TracerProvider() }))
 }
+
+func TestSpanSpanContext(t *testing.T) {
+	s := spanBuilder{SpanContext: spanContext0}.Build()
+	assert.Equal(t, spanContext0, s.SpanContext())
+}
+
+type spanBuilder struct {
+	Name        string
+	NotSampled  bool
+	SpanContext trace.SpanContext
+	Options     []trace.SpanStartOption
+}
+
+func (b spanBuilder) Build() *span {
+	tracer := new(tracer)
+	s := &span{sampled: !b.NotSampled, spanContext: b.SpanContext}
+	s.traces, s.span = tracer.traces(
+		context.Background(),
+		b.Name,
+		trace.NewSpanStartConfig(b.Options...),
+		s.spanContext,
+		trace.SpanContext{},
+	)
+
+	return s
+}