add context tests

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

tracer/context_test.go

@@ -0,0 +1,25 @@
+package tracer
+
+import (
+	"context"
+	"testing"
+)
+
+func TestFromContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(),tracerKey{}, NewTracer())
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromContext not works")
+	}
+}
+
+func TestNewContext(t *testing.T) {
+	ctx := NewContext(context.TODO(), NewTracer())
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewContext not works")
+	}
+}
+