Add test to check that client.SolveOpt.LocalDirs still works

It will need to be removed in a follow up PR.

Signed-off-by: Leandro Santiago <leandrosansilva@gmail.com>

Author: leandrosansilva

client/client_test.go

@@ -211,6 +211,7 @@ var allTests = []func(t *testing.T, sb integration.Sandbox){
 	testSnapshotWithMultipleBlobs,
 	testExportLocalNoPlatformSplit,
 	testExportLocalNoPlatformSplitOverwrite,
+	testSolverOptLocalDirsStillWorks,
 }
 
 func TestIntegration(t *testing.T) {
@@ -1555,6 +1556,49 @@ func testRelativeWorkDir(t *testing.T, sb integration.Sandbox) {
 	require.Equal(t, []byte("/test1/test2\n"), dt)
 }
 
+// TODO: remove this test once `client.SolveOpt.LocalDirs`, now marked as deprecated, is removed.
+// For more context on this test, please check:
+// https://github.com/moby/buildkit/pull/4583#pullrequestreview-1847043452
+func testSolverOptLocalDirsStillWorks(t *testing.T, sb integration.Sandbox) {
+	integration.SkipOnPlatform(t, "windows")
+
+	c, err := New(sb.Context(), sb.Address())
+	require.NoError(t, err)
+	defer c.Close()
+
+	out := llb.Image("docker.io/library/busybox:latest").
+		File(llb.Copy(llb.Local("mylocal"), "input.txt", "input.txt")).
+		Run(llb.Shlex(`sh -c "/bin/rev < input.txt > /out/output.txt"`)).
+		AddMount(`/out`, llb.Scratch())
+
+	def, err := out.Marshal(sb.Context())
+	require.NoError(t, err)
+
+	srcDir := integration.Tmpdir(t,
+		fstest.CreateFile("input.txt", []byte("Hello World"), 0600),
+	)
+
+	destDir := integration.Tmpdir(t)
+
+	_, err = c.Solve(sb.Context(), def, SolveOpt{
+		LocalDirs: map[string]string{
+			"mylocal": srcDir.Name,
+		},
+		Exports: []ExportEntry{
+			{
+				Type:      ExporterLocal,
+				OutputDir: destDir.Name,
+			},
+		},
+	}, nil)
+
+	require.NoError(t, err)
+
+	dt, err := os.ReadFile(filepath.Join(destDir.Name, "output.txt"))
+	require.NoError(t, err)
+	require.Equal(t, []byte("dlroW olleH"), dt)
+}
+
 func testFileOpMkdirMkfile(t *testing.T, sb integration.Sandbox) {
 	requiresLinux(t)
 	c, err := New(sb.Context(), sb.Address())