Testing: create new daemon (only) if needed

Some tests were skipped if the local daemon did not have
experimental features enabled; at the same time, some tests
unconditionally created a new (experimental) daemon, even if
the local daemon already had experimental enabled.

This patch;

- Checks if the "testEnv" is an experimental Linux daemon
- If not, and the daemon is running locally; spin up a new
  experimental daemon to be used during the test.

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

integration/build/build_session_test.go

@@ -21,13 +21,19 @@ import (
 )
 
 func TestBuildWithSession(t *testing.T) {
-	skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
 	skip.If(t, testEnv.DaemonInfo.OSType == "windows")
+
+	var client dclient.APIClient
+	if !testEnv.DaemonInfo.ExperimentalBuild {
+		skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
+
 		d := daemon.New(t, daemon.WithExperimental)
 		d.StartWithBusybox(t)
 		defer d.Stop(t)
-
-	client := d.NewClientT(t)
+		client = d.NewClientT(t)
+	} else {
+		client = testEnv.APIClient()
+	}
 
 	dockerfile := `
 		FROM busybox

integration/build/build_squash_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 
 	"github.com/docker/docker/api/types"
+	dclient "github.com/docker/docker/client"
 	"github.com/docker/docker/integration/internal/container"
 	"github.com/docker/docker/internal/test/daemon"
 	"github.com/docker/docker/internal/test/fakecontext"
@@ -20,13 +21,18 @@ import (
 
 func TestBuildSquashParent(t *testing.T) {
 	skip.If(t, testEnv.DaemonInfo.OSType == "windows")
-	skip.If(t, !testEnv.DaemonInfo.ExperimentalBuild)
+
+	var client dclient.APIClient
+	if !testEnv.DaemonInfo.ExperimentalBuild {
 		skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
+
 		d := daemon.New(t, daemon.WithExperimental)
 		d.StartWithBusybox(t)
 		defer d.Stop(t)
-
-	client := d.NewClientT(t)
+		client = d.NewClientT(t)
+	} else {
+		client = testEnv.APIClient()
+	}
 
 	dockerfile := `
 		FROM busybox

integration/session/session_test.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 	"testing"
 
+	"github.com/docker/docker/internal/test/daemon"
 	req "github.com/docker/docker/internal/test/request"
 	"gotest.tools/assert"
 	is "gotest.tools/assert/cmp"
@@ -11,16 +12,27 @@ import (
 )
 
 func TestSessionCreate(t *testing.T) {
-	skip.If(t, !testEnv.DaemonInfo.ExperimentalBuild)
 	skip.If(t, testEnv.OSType == "windows", "FIXME")
 
 	defer setupTest(t)()
+	daemonHost := req.DaemonHost()
+	if !testEnv.DaemonInfo.ExperimentalBuild {
+		skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
 
-	res, body, err := req.Post("/session", req.With(func(r *http.Request) error {
+		d := daemon.New(t, daemon.WithExperimental)
+		d.StartWithBusybox(t)
+		defer d.Stop(t)
+		daemonHost = d.Sock()
+	}
+
+	res, body, err := req.Post("/session",
+		req.Host(daemonHost),
+		req.With(func(r *http.Request) error {
 			r.Header.Set("X-Docker-Expose-Session-Uuid", "testsessioncreate") // so we don't block default name if something else is using it
 			r.Header.Set("Upgrade", "h2c")
 			return nil
-	}))
+		}),
+	)
 	assert.NilError(t, err)
 	assert.NilError(t, body.Close())
 	assert.Check(t, is.DeepEqual(res.StatusCode, http.StatusSwitchingProtocols))
@@ -28,20 +40,33 @@ func TestSessionCreate(t *testing.T) {
 }
 
 func TestSessionCreateWithBadUpgrade(t *testing.T) {
-	skip.If(t, !testEnv.DaemonInfo.ExperimentalBuild)
 	skip.If(t, testEnv.OSType == "windows", "FIXME")
 
-	res, body, err := req.Post("/session")
+	defer setupTest(t)()
+	daemonHost := req.DaemonHost()
+	if !testEnv.DaemonInfo.ExperimentalBuild {
+		skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
+
+		d := daemon.New(t, daemon.WithExperimental)
+		d.StartWithBusybox(t)
+		defer d.Stop(t)
+		daemonHost = d.Sock()
+	}
+
+	res, body, err := req.Post("/session", req.Host(daemonHost))
 	assert.NilError(t, err)
 	assert.Check(t, is.DeepEqual(res.StatusCode, http.StatusBadRequest))
 	buf, err := req.ReadBody(body)
 	assert.NilError(t, err)
 	assert.Check(t, is.Contains(string(buf), "no upgrade"))
 
-	res, body, err = req.Post("/session", req.With(func(r *http.Request) error {
+	res, body, err = req.Post("/session",
+		req.Host(daemonHost),
+		req.With(func(r *http.Request) error {
 			r.Header.Set("Upgrade", "foo")
 			return nil
-	}))
+		}),
+	)
 	assert.NilError(t, err)
 	assert.Check(t, is.DeepEqual(res.StatusCode, http.StatusBadRequest))
 	buf, err = req.ReadBody(body)

internal/test/daemon/daemon.go

@@ -88,6 +88,7 @@ func New(t testingT, ops ...func(*Daemon)) *Daemon {
 	if ht, ok := t.(test.HelperT); ok {
 		ht.Helper()
 	}
+	t.Log("Creating a new daemon")
 	dest := os.Getenv("DOCKER_INTEGRATION_DAEMON_DEST")
 	if dest == "" {
 		dest = os.Getenv("DEST")