Update TestUpdatePidsLimit to be more atomic

Create a new container for each subtest, so that individual
subtests are self-contained, and there's no need to execute
them in the exact order, or resetting the container in between.

This makes the test slower (6.54s vs  3.43s), but reduced the
difference by using `network=host`, which made a substantial
difference (without `network=host`, the test took more than
twice as long: 13.96s).

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

integration/container/update_linux_test.go

@@ -7,7 +7,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/docker/docker/api/types"
 	containertypes "github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/client"
 	"github.com/docker/docker/integration/internal/container"
@@ -114,8 +113,6 @@ func TestUpdatePidsLimit(t *testing.T) {
 	oldAPIclient := request.NewAPIClient(t, client.WithVersion("1.24"))
 	ctx := context.Background()
 
-	cID := container.Run(t, ctx, apiClient)
-
 	intPtr := func(i int64) *int64 {
 		return &i
 	}
@@ -123,33 +120,28 @@ func TestUpdatePidsLimit(t *testing.T) {
 	for _, test := range []struct {
 		desc     string
 		oldAPI   bool
+		initial  *int64
 		update   *int64
 		expect   int64
 		expectCg string
 	}{
 		{desc: "update from none", update: intPtr(32), expect: 32, expectCg: "32"},
-		{desc: "no change", update: nil, expectCg: "32"},
-		{desc: "update lower", update: intPtr(16), expect: 16, expectCg: "16"},
-		{desc: "update on old api ignores value", oldAPI: true, update: intPtr(10), expect: 16, expectCg: "16"},
-		{desc: "unset limit", update: intPtr(0), expect: 0, expectCg: "max"},
-		{desc: "reset", update: intPtr(32), expect: 32, expectCg: "32"},
-		{desc: "unset limit with minus one", update: intPtr(-1), expect: 0, expectCg: "max"},
-		{desc: "reset", update: intPtr(32), expect: 32, expectCg: "32"},
-		{desc: "unset limit with minus two", update: intPtr(-2), expect: 0, expectCg: "max"},
+		{desc: "no change", initial: intPtr(32), expect: 32, expectCg: "32"},
+		{desc: "update lower", initial: intPtr(32), update: intPtr(16), expect: 16, expectCg: "16"},
+		{desc: "update on old api ignores value", oldAPI: true, initial: intPtr(32), update: intPtr(16), expect: 32, expectCg: "32"},
+		{desc: "unset limit with zero", initial: intPtr(32), update: intPtr(0), expect: 0, expectCg: "max"},
+		{desc: "unset limit with minus one", initial: intPtr(32), update: intPtr(-1), expect: 0, expectCg: "max"},
+		{desc: "unset limit with minus two", initial: intPtr(32), update: intPtr(-2), expect: 0, expectCg: "max"},
 	} {
 		c := apiClient
 		if test.oldAPI {
 			c = oldAPIclient
 		}
 
-		var before types.ContainerJSON
-		if test.update == nil {
-			var err error
-			before, err = c.ContainerInspect(ctx, cID)
-			assert.NilError(t, err)
-		}
-
 		t.Run(test.desc, func(t *testing.T) {
+			// Using "network=host" to speed up creation (13.96s vs 6.54s)
+			cID := container.Run(t, ctx, apiClient, container.WithPidsLimit(test.initial), container.WithNetworkMode("host"))
+
 			_, err := c.ContainerUpdate(ctx, cID, containertypes.UpdateConfig{
 				Resources: containertypes.Resources{
 					PidsLimit: test.update,
@@ -160,13 +152,7 @@ func TestUpdatePidsLimit(t *testing.T) {
 			inspect, err := c.ContainerInspect(ctx, cID)
 			assert.NilError(t, err)
 			assert.Assert(t, inspect.HostConfig.Resources.PidsLimit != nil)
-
-			if test.update == nil {
-				assert.Assert(t, before.HostConfig.Resources.PidsLimit != nil)
-				assert.Equal(t, *before.HostConfig.Resources.PidsLimit, *inspect.HostConfig.Resources.PidsLimit)
-			} else {
-				assert.Equal(t, *inspect.HostConfig.Resources.PidsLimit, test.expect)
-			}
+			assert.Equal(t, *inspect.HostConfig.Resources.PidsLimit, test.expect)
 
 			ctx, cancel := context.WithTimeout(ctx, 60*time.Second)
 			defer cancel()

integration/internal/container/ops.go

@@ -137,6 +137,16 @@ func WithAutoRemove(c *TestContainerConfig) {
 	c.HostConfig.AutoRemove = true
 }
 
+// WithPidsLimit sets the container's "pids-limit
+func WithPidsLimit(limit *int64) func(*TestContainerConfig) {
+	return func(c *TestContainerConfig) {
+		if c.HostConfig == nil {
+			c.HostConfig = &containertypes.HostConfig{}
+		}
+		c.HostConfig.PidsLimit = limit
+	}
+}
+
 // WithRestartPolicy sets container's restart policy
 func WithRestartPolicy(policy string) func(c *TestContainerConfig) {
 	return func(c *TestContainerConfig) {