fix race condition in TestRemoveForce

This test uses two subtests that were sharing the same variable.
Subtests run in a goroutine, which could lead to them concurrently
accessing the variable, resulting in a panic:

    === FAIL: cli/command/container TestRemoveForce/without_force (0.00s)
    Error: Error: No such container: nosuchcontainer
        --- FAIL: TestRemoveForce/without_force (0.00s)
    panic: runtime error: invalid memory address or nil pointer dereference [recovered]
    	panic: runtime error: invalid memory address or nil pointer dereference
    [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x40393f]
    goroutine 190 [running]:
    testing.tRunner.func1.2({0xb76380, 0x124c9a0})
    	/usr/local/go/src/testing/testing.go:1389 +0x24e
    testing.tRunner.func1()
    	/usr/local/go/src/testing/testing.go:1392 +0x39f
    panic({0xb76380, 0x124c9a0})
    	/usr/local/go/src/runtime/panic.go:838 +0x207
    sort.StringSlice.Less(...)
    	/usr/local/go/src/sort/sort.go:319
    sort.insertionSort({0xd87380, 0xc00051b3b0}, 0x0, 0x2)
    	/usr/local/go/src/sort/sort.go:40 +0xb1
    sort.quickSort({0xd87380, 0xc00051b3b0}, 0x18?, 0xb4f060?, 0xc000540e01?)
    	/usr/local/go/src/sort/sort.go:222 +0x171
    sort.Sort({0xd87380, 0xc00051b3b0})
    	/usr/local/go/src/sort/sort.go:231 +0x53
    sort.Strings(...)
    	/usr/local/go/src/sort/sort.go:335
    github.com/docker/cli/cli/command/container.TestRemoveForce.func2(0xc0005389c0?)
    	/go/src/github.com/docker/cli/cli/command/container/rm_test.go:36 +0x125
    testing.tRunner(0xc00053e4e0, 0xc00051b140)
    	/usr/local/go/src/testing/testing.go:1439 +0x102
    created by testing.(*T).Run
    	/usr/local/go/src/testing/testing.go:1486 +0x35f
    === FAIL: cli/command/container TestRemoveForce (0.00s)

This patch changes the test to use to separate variables.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 9688f62)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/container/rm_test.go

@@ -14,13 +14,17 @@ import (
 )
 
 func TestRemoveForce(t *testing.T) {
-	var removed []string
+	var (
+		removed1 []string
+		removed2 []string
+	)
 
 	cli := test.NewFakeCli(&fakeClient{
 		containerRemoveFunc: func(ctx context.Context, container string, options types.ContainerRemoveOptions) error {
-			removed = append(removed, container)
+			removed1 = append(removed1, container)
+			removed2 = append(removed2, container)
 			if container == "nosuchcontainer" {
-				return errdefs.NotFound(fmt.Errorf("Error: No such container: " + container))
+				return errdefs.NotFound(fmt.Errorf("Error: no such container: " + container))
 			}
 			return nil
 		},
@@ -31,16 +35,16 @@ func TestRemoveForce(t *testing.T) {
 
 	t.Run("without force", func(t *testing.T) {
 		cmd.SetArgs([]string{"nosuchcontainer", "mycontainer"})
-		removed = []string{}
-		assert.ErrorContains(t, cmd.Execute(), "No such container")
-		sort.Strings(removed)
-		assert.DeepEqual(t, removed, []string{"mycontainer", "nosuchcontainer"})
+		removed1 = []string{}
+		assert.ErrorContains(t, cmd.Execute(), "no such container")
+		sort.Strings(removed1)
+		assert.DeepEqual(t, removed1, []string{"mycontainer", "nosuchcontainer"})
 	})
 	t.Run("with force", func(t *testing.T) {
 		cmd.SetArgs([]string{"--force", "nosuchcontainer", "mycontainer"})
-		removed = []string{}
+		removed2 = []string{}
 		assert.NilError(t, cmd.Execute())
-		sort.Strings(removed)
-		assert.DeepEqual(t, removed, []string{"mycontainer", "nosuchcontainer"})
+		sort.Strings(removed2)
+		assert.DeepEqual(t, removed2, []string{"mycontainer", "nosuchcontainer"})
 	})
 }