diff --git a/tracing/opentracing/endpoint_test.go b/tracing/opentracing/endpoint_test.go
index 02da72e27..d89136c93 100644
--- a/tracing/opentracing/endpoint_test.go
+++ b/tracing/opentracing/endpoint_test.go
@@ -18,24 +18,23 @@ func TestTraceServer(t *testing.T) {
 	contextSpan := tracer.StartSpan("").(*mocktracer.MockSpan)
 	ctx := opentracing.ContextWithSpan(context.Background(), contextSpan)
 
-	var innerEndpoint endpoint.Endpoint
-	innerEndpoint = func(context.Context, interface{}) (interface{}, error) {
-		return struct{}{}, nil
-	}
-	tracedEndpoint := kitot.TraceServer(tracer, "testOp")(innerEndpoint)
+	tracedEndpoint := kitot.TraceServer(tracer, "testOp")(endpoint.Nop)
 	if _, err := tracedEndpoint(ctx, struct{}{}); err != nil {
 		t.Fatal(err)
 	}
-	if want, have := 1, len(tracer.FinishedSpans); want != have {
+
+	finishedSpans := tracer.GetFinishedSpans()
+	if want, have := 1, len(finishedSpans); want != have {
 		t.Fatalf("Want %v span(s), found %v", want, have)
 	}
 
-	endpointSpan := tracer.FinishedSpans[0]
 	// Test that the op name is updated
+	endpointSpan := finishedSpans[0]
 	if want, have := "testOp", endpointSpan.OperationName; want != have {
 		t.Fatalf("Want %q, have %q", want, have)
 	}
-	// ... and that the ID is unmodified.
+
+	// ...and that the ID is unmodified.
 	if want, have := contextSpan.SpanID, endpointSpan.SpanID; want != have {
 		t.Errorf("Want SpanID %q, have %q", want, have)
 	}
@@ -44,21 +43,19 @@ func TestTraceServer(t *testing.T) {
 func TestTraceServerNoContextSpan(t *testing.T) {
 	tracer := mocktracer.New()
 
-	var innerEndpoint endpoint.Endpoint
-	innerEndpoint = func(context.Context, interface{}) (interface{}, error) {
-		return struct{}{}, nil
-	}
-	tracedEndpoint := kitot.TraceServer(tracer, "testOp")(innerEndpoint)
-	// Empty/background context:
+	// Empty/background context.
+	tracedEndpoint := kitot.TraceServer(tracer, "testOp")(endpoint.Nop)
 	if _, err := tracedEndpoint(context.Background(), struct{}{}); err != nil {
 		t.Fatal(err)
 	}
-	// tracedEndpoint created a new Span:
-	if want, have := 1, len(tracer.FinishedSpans); want != have {
+
+	// tracedEndpoint created a new Span.
+	finishedSpans := tracer.GetFinishedSpans()
+	if want, have := 1, len(finishedSpans); want != have {
 		t.Fatalf("Want %v span(s), found %v", want, have)
 	}
 
-	endpointSpan := tracer.FinishedSpans[0]
+	endpointSpan := finishedSpans[0]
 	if want, have := "testOp", endpointSpan.OperationName; want != have {
 		t.Fatalf("Want %q, have %q", want, have)
 	}
@@ -72,23 +69,22 @@ func TestTraceClient(t *testing.T) {
 	defer parentSpan.Finish()
 	ctx := opentracing.ContextWithSpan(context.Background(), parentSpan)
 
-	var innerEndpoint endpoint.Endpoint
-	innerEndpoint = func(context.Context, interface{}) (interface{}, error) {
-		return struct{}{}, nil
-	}
-	tracedEndpoint := kitot.TraceClient(tracer, "testOp")(innerEndpoint)
+	tracedEndpoint := kitot.TraceClient(tracer, "testOp")(endpoint.Nop)
 	if _, err := tracedEndpoint(ctx, struct{}{}); err != nil {
 		t.Fatal(err)
 	}
-	// tracedEndpoint created a new Span:
-	if want, have := 1, len(tracer.FinishedSpans); want != have {
+
+	// tracedEndpoint created a new Span.
+	finishedSpans := tracer.GetFinishedSpans()
+	if want, have := 1, len(finishedSpans); want != have {
 		t.Fatalf("Want %v span(s), found %v", want, have)
 	}
 
-	endpointSpan := tracer.FinishedSpans[0]
+	endpointSpan := finishedSpans[0]
 	if want, have := "testOp", endpointSpan.OperationName; want != have {
 		t.Fatalf("Want %q, have %q", want, have)
 	}
+
 	// ... and that the parent ID is set appropriately.
 	if want, have := parentSpan.SpanID, endpointSpan.ParentID; want != have {
 		t.Errorf("Want ParentID %q, have %q", want, have)
diff --git a/tracing/opentracing/grpc_test.go b/tracing/opentracing/grpc_test.go
index d9de49b05..2db9db373 100644
--- a/tracing/opentracing/grpc_test.go
+++ b/tracing/opentracing/grpc_test.go
@@ -9,7 +9,6 @@ import (
 	"google.golang.org/grpc/metadata"
 
 	kitot "github.com/go-kit/kit/tracing/opentracing"
-	"github.com/go-kit/kit/transport/grpc"
 )
 
 func TestTraceGRPCRequestRoundtrip(t *testing.T) {
@@ -21,7 +20,7 @@ func TestTraceGRPCRequestRoundtrip(t *testing.T) {
 	beforeSpan.SetBaggageItem("baggage", "check")
 	beforeCtx := opentracing.ContextWithSpan(context.Background(), beforeSpan)
 
-	var toGRPCFunc grpc.RequestFunc = kitot.ToGRPCRequest(tracer, nil)
+	toGRPCFunc := kitot.ToGRPCRequest(tracer, nil)
 	md := metadata.Pairs()
 	// Call the RequestFunc.
 	afterCtx := toGRPCFunc(beforeCtx, &md)
@@ -33,12 +32,13 @@ func TestTraceGRPCRequestRoundtrip(t *testing.T) {
 	}
 
 	// No spans should have finished yet.
-	if want, have := 0, len(tracer.FinishedSpans); want != have {
+	finishedSpans := tracer.GetFinishedSpans()
+	if want, have := 0, len(finishedSpans); want != have {
 		t.Errorf("Want %v span(s), found %v", want, have)
 	}
 
 	// Use FromGRPCRequest to verify that we can join with the trace given MD.
-	var fromGRPCFunc grpc.RequestFunc = kitot.FromGRPCRequest(tracer, "joined", nil)
+	fromGRPCFunc := kitot.FromGRPCRequest(tracer, "joined", nil)
 	joinCtx := fromGRPCFunc(afterCtx, &md)
 	joinedSpan := opentracing.SpanFromContext(joinCtx).(*mocktracer.MockSpan)
 
diff --git a/tracing/opentracing/http_test.go b/tracing/opentracing/http_test.go
index d49acbfd6..a6f22bf78 100644
--- a/tracing/opentracing/http_test.go
+++ b/tracing/opentracing/http_test.go
@@ -9,7 +9,6 @@ import (
 	"golang.org/x/net/context"
 
 	kitot "github.com/go-kit/kit/tracing/opentracing"
-	kithttp "github.com/go-kit/kit/transport/http"
 )
 
 func TestTraceHTTPRequestRoundtrip(t *testing.T) {
@@ -21,7 +20,7 @@ func TestTraceHTTPRequestRoundtrip(t *testing.T) {
 	beforeSpan.SetBaggageItem("baggage", "check")
 	beforeCtx := opentracing.ContextWithSpan(context.Background(), beforeSpan)
 
-	var toHTTPFunc kithttp.RequestFunc = kitot.ToHTTPRequest(tracer, nil)
+	toHTTPFunc := kitot.ToHTTPRequest(tracer, nil)
 	req, _ := http.NewRequest("GET", "http://test.biz/url", nil)
 	// Call the RequestFunc.
 	afterCtx := toHTTPFunc(beforeCtx, req)
@@ -33,12 +32,13 @@ func TestTraceHTTPRequestRoundtrip(t *testing.T) {
 	}
 
 	// No spans should have finished yet.
-	if want, have := 0, len(tracer.FinishedSpans); want != have {
+	finishedSpans := tracer.GetFinishedSpans()
+	if want, have := 0, len(finishedSpans); want != have {
 		t.Errorf("Want %v span(s), found %v", want, have)
 	}
 
 	// Use FromHTTPRequest to verify that we can join with the trace given a req.
-	var fromHTTPFunc kithttp.RequestFunc = kitot.FromHTTPRequest(tracer, "joined", nil)
+	fromHTTPFunc := kitot.FromHTTPRequest(tracer, "joined", nil)
 	joinCtx := fromHTTPFunc(afterCtx, req)
 	joinedSpan := opentracing.SpanFromContext(joinCtx).(*mocktracer.MockSpan)