@@ -5,9 +5,11 @@ import (

 	"fmt"

 	"io"

 	"net/http"

+	"runtime"

 	"strconv"

 	"strings"

+	"github.com/moby/moby/api/types/build"

 	"github.com/moby/moby/api/types/common"

 	"github.com/moby/moby/api/types/swarm"

 )

@@ -60,9 +62,71 @@ func ensureBody(f func(req *http.Request) (*http.Response, error)) testRoundTrip

 	}

 }

-// WithMockClient is a test helper that allows you to inject a mock client for testing.

+// makeTestRoundTripper makes sure the response has a Body, using [http.NoBody] if

+// none is present, and returns it as a testRoundTripper. If withDefaults is set,

+// it also mocks the "/_ping" endpoint and sets default headers as returned

+// by the daemon.

+func makeTestRoundTripper(f func(req *http.Request) (*http.Response, error)) testRoundTripper {

+	return func(req *http.Request) (*http.Response, error) {

+		if req.URL.Path == "/_ping" {

+			return mockPingResponse(http.StatusOK, PingResult{

+				APIVersion:     MaxAPIVersion,

+				OSType:         runtime.GOOS,

+				Experimental:   true,

+				BuilderVersion: build.BuilderBuildKit,

+				SwarmStatus: &SwarmStatus{

+					NodeState:        swarm.LocalNodeStateActive,

+					ControlAvailable: true,

+				},

+			})(req)

+		}

+		resp, err := f(req)

+		if resp != nil {

+			if resp.Body == nil {

+				resp.Body = http.NoBody

+			}

+			if resp.Request == nil {

+				resp.Request = req

+			}

+		}

+		applyDefaultHeaders(resp)

+		return resp, err

+	}

+}

+

+// applyDefaultHeaders mocks the headers set by the daemon's VersionMiddleware.

+func applyDefaultHeaders(resp *http.Response) {

+	if resp == nil {

+		return

+	}

+	if resp.Header == nil {

+		resp.Header = make(http.Header)

+	}

+	if resp.Header.Get("Server") == "" {

+		resp.Header.Set("Server", fmt.Sprintf("Docker/%s (%s)", "v99.99.99", runtime.GOOS))

+	}

+	if resp.Header.Get("Api-Version") == "" {

+		resp.Header.Set("Api-Version", MaxAPIVersion)

+	}

+	if resp.Header.Get("Ostype") == "" {

+		resp.Header.Set("Ostype", runtime.GOOS)

+	}

+}

+

+// WithMockClient is a test helper that allows you to inject a mock client for

+// testing. By default, it mocks the "/_ping" endpoint, so allow the client

+// to perform API-version negotiation. Other endpoints are handled by "doer".

 func WithMockClient(doer func(*http.Request) (*http.Response, error)) Opt {

 	return WithHTTPClient(&http.Client{

+		Transport: makeTestRoundTripper(doer),

+	})

+}

+

+// WithBaseMockClient is a test helper that allows you to inject a mock client

+// for testing. It is identical to [WithMockClient], but does not mock the "/_ping"

+// endpoint, and doesn't set the default headers.

+func WithBaseMockClient(doer func(*http.Request) (*http.Response, error)) Opt {

+	return WithHTTPClient(&http.Client{

 		Transport: ensureBody(doer),

 	})

 }

@@ -258,7 +258,7 @@ func TestNegotiateAPIVersionEmpty(t *testing.T) {

 	client, err := New(FromEnv,

 		WithAPIVersionNegotiation(),

-		WithMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: expected})),

+		WithBaseMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: expected})),

 	)

 	assert.NilError(t, err)

@@ -331,7 +331,7 @@ func TestNegotiateAPIVersion(t *testing.T) {

 			opts := []Opt{

 				FromEnv,

 				WithAPIVersionNegotiation(),

-				WithMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: tc.pingVersion})),

+				WithBaseMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: tc.pingVersion})),

 			}

 			if tc.clientVersion != "" {

@@ -363,7 +363,7 @@ func TestNegotiateAPIVersionOverride(t *testing.T) {

 	client, err := New(

 		FromEnv,

-		WithMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: "1.45"})),

+		WithBaseMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: "1.45"})),

 	)

 	assert.NilError(t, err)

@@ -393,7 +393,7 @@ func TestNegotiateAPIVersionAutomatic(t *testing.T) {

 	ctx := t.Context()

 	client, err := New(

-		WithMockClient(func(req *http.Request) (*http.Response, error) {

+		WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 			return mockPingResponse(http.StatusOK, PingResult{APIVersion: pingVersion})(req)

 		}),

 		WithAPIVersionNegotiation(),

@@ -422,7 +422,7 @@ func TestNegotiateAPIVersionAutomatic(t *testing.T) {

 func TestNegotiateAPIVersionWithEmptyVersion(t *testing.T) {

 	client, err := New(

 		WithAPIVersion(""),

-		WithMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: "1.50"})),

+		WithBaseMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: "1.50"})),

 	)

 	assert.NilError(t, err)

@@ -442,7 +442,7 @@ func TestNegotiateAPIVersionWithFixedVersion(t *testing.T) {

 	)

 	client, err := New(

 		WithAPIVersion(customVersion),

-		WithMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: pingVersion})),

+		WithBaseMockClient(mockPingResponse(http.StatusOK, PingResult{APIVersion: pingVersion})),

 	)

 	assert.NilError(t, err)

@@ -18,7 +18,7 @@ import (

 // panics.

 func TestPingFail(t *testing.T) {

 	var withHeader bool

-	client, err := New(WithMockClient(func(req *http.Request) (*http.Response, error) {

+	client, err := New(WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 		var hdr http.Header

 		if withHeader {

 			hdr = http.Header{}

@@ -48,7 +48,7 @@ func TestPingFail(t *testing.T) {

 // TestPingWithError tests the case where there is a protocol error in the ping.

 // This test is mostly just testing that there are no panics in this code path.

 func TestPingWithError(t *testing.T) {

-	client, err := New(WithMockClient(func(req *http.Request) (*http.Response, error) {

+	client, err := New(WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 		return nil, errors.New("some connection error")

 	}))

 	assert.NilError(t, err)

@@ -64,7 +64,7 @@ func TestPingWithError(t *testing.T) {

 // TestPingSuccess tests that we are able to get the expected API headers/ping

 // details on success.

 func TestPingSuccess(t *testing.T) {

-	client, err := New(WithMockClient(func(req *http.Request) (*http.Response, error) {

+	client, err := New(WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 		hdr := http.Header{}

 		hdr.Set("Api-Version", "awesome")

 		hdr.Set("Docker-Experimental", "true")

@@ -110,7 +110,7 @@ func TestPingHeadFallback(t *testing.T) {

 	for _, tc := range tests {

 		t.Run(http.StatusText(tc.status), func(t *testing.T) {

 			var reqs []string

-			client, err := New(WithMockClient(func(req *http.Request) (*http.Response, error) {

+			client, err := New(WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 				if !strings.HasPrefix(req.URL.Path, expectedPath) {

 					return nil, fmt.Errorf("expected URL '%s', got '%s'", expectedPath, req.URL.Path)

 				}

@@ -194,7 +194,7 @@ func TestResponseErrors(t *testing.T) {

 	}

 	for _, tc := range tests {

 		t.Run(tc.doc, func(t *testing.T) {

-			client, err := New(WithMockClient(func(req *http.Request) (*http.Response, error) {

+			client, err := New(WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 				return mockResponse(http.StatusBadRequest, http.Header{"Content-Type": []string{tc.contentType}}, tc.response)(req)

 			}))

 			if tc.apiVersion != "" {

@@ -210,7 +210,7 @@ func TestResponseErrors(t *testing.T) {

 func TestInfiniteError(t *testing.T) {

 	infinitR := rand.New(rand.NewSource(42))

-	client, err := New(WithMockClient(func(req *http.Request) (*http.Response, error) {

+	client, err := New(WithBaseMockClient(func(req *http.Request) (*http.Response, error) {

 		resp := &http.Response{

 			StatusCode: http.StatusInternalServerError,

 			Header:     http.Header{},