net/http: dispatch the client through its RoundTripper (fetch on js/wasm)

http/client.go

@@ -158,7 +158,7 @@ func (c *Client) send(req *Request, deadline time.Time) (resp *Response, didTime
 			req.AddCookie(cookie)
 		}
 	}
-	resp, didTimeout, err = send(req, deadline)
+	resp, didTimeout, err = send(req, c.transport(), deadline)
 	if err != nil {
 		return nil, didTimeout, err
 	}
@@ -177,11 +177,16 @@ func (c *Client) deadline() time.Time {
 	return time.Time{}
 }
 
+func (c *Client) transport() RoundTripper {
+	if c.Transport != nil {
+		return c.Transport
+	}
+	return DefaultTransport
+}
+
 // send issues an HTTP request.
 // Caller should close resp.Body when done reading from it.
-func send(req *Request, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {
-
-	// TINYGO: Removed round tripper
+func send(req *Request, rt RoundTripper, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {
 
 	if req.URL == nil {
 		req.closeBody()
@@ -192,6 +197,10 @@ func send(req *Request, deadline time.Time) (resp *Response, didTimeout func() b
 		req.closeBody()
 		return nil, alwaysFalse, errors.New("http: Request.RequestURI can't be set in client requests")
 	}
+	if rt == nil {
+		req.closeBody()
+		return nil, alwaysFalse, errors.New("http: no Client.Transport or DefaultTransport")
+	}
 
 	// TINYGO: Removed forkReq stuff
 
@@ -208,7 +217,7 @@ func send(req *Request, deadline time.Time) (resp *Response, didTimeout func() b
 		req.Header.Set("Authorization", "Basic "+basicAuth(username, password))
 	}
 
-	resp, err = roundTrip(req)
+	resp, err = rt.RoundTrip(req)
 	if err != nil {
 
 		// TINYGO: Remove TLS error check
@@ -440,10 +449,6 @@ func urlErrorOp(method string) string {
 // Any returned error will be of type [*url.Error]. The url.Error
 // value's Timeout method will report true if the request timed out.
 func (c *Client) Do(req *Request) (*Response, error) {
-	if c.Transport != nil {
-		return c.Transport.RoundTrip(req)
-	}
-
 	return c.do(req)
 }
 

http/clienttransport_test.go

@@ -0,0 +1,72 @@
+package http
+
+import (
+	"io"
+	"strings"
+	"testing"
+)
+
+type recordingTransport struct {
+	calls int
+	req   *Request
+}
+
+func (t *recordingTransport) RoundTrip(req *Request) (*Response, error) {
+	t.calls++
+	t.req = req
+	return &Response{
+		Status:     "200 OK",
+		StatusCode: 200,
+		Header:     Header{},
+		Body:       io.NopCloser(strings.NewReader("ok")),
+		Request:    req,
+	}, nil
+}
+
+// A client with no Transport must dispatch through DefaultTransport, whose
+// RoundTrip is build-tagged: the fetch API on js/wasm, the netdev dial
+// elsewhere. Dispatching to the package-level dialer directly is issue #66.
+func TestClientUsesDefaultTransport(t *testing.T) {
+	previous := DefaultTransport
+	defer func() { DefaultTransport = previous }()
+	rt := &recordingTransport{}
+	DefaultTransport = rt
+
+	c := &Client{}
+	resp, err := c.Get("http://example.com/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+	if rt.calls != 1 {
+		t.Fatalf("DefaultTransport.RoundTrip calls = %d, want 1", rt.calls)
+	}
+	if rt.req.URL.Host != "example.com" {
+		t.Fatalf("request URL = %v", rt.req.URL)
+	}
+}
+
+func TestClientUsesExplicitTransport(t *testing.T) {
+	rt := &recordingTransport{}
+	c := &Client{Transport: rt}
+	resp, err := c.Get("http://example.com/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+	if rt.calls != 1 {
+		t.Fatalf("Transport.RoundTrip calls = %d, want 1", rt.calls)
+	}
+}
+
+func TestClientNoTransport(t *testing.T) {
+	previous := DefaultTransport
+	defer func() { DefaultTransport = previous }()
+	DefaultTransport = nil
+
+	c := &Client{}
+	_, err := c.Get("http://example.com/")
+	if err == nil || !strings.Contains(err.Error(), "no Client.Transport or DefaultTransport") {
+		t.Fatalf("error = %v, want no-transport error", err)
+	}
+}