client: improve mocking responses

Make the mocked responses match the API closer;

- Add headers as returned by the daemon's VersionMiddleware
- By default handle "/_ping" requests to allow the client to
  perform API-version negotiation as part of tests.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/client_mock_test.go

@@ -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"
 )
@@ -60,8 +62,70 @@ 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),
 	})

client/client_test.go

@@ -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)
 

client/ping_test.go

@@ -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)
 				}

client/request_test.go

@@ -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{},