command: change drive to lowercase for wsl path

On Windows, the drive casing doesn't matter outside of WSL. For WSL, the
drives are lowercase. When we're producing a WSL path, lowercase the
drive letter.

Co-authored-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>
Co-authored-by: Laura Brehm <laurabrehm@hey.com>

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>
Signed-off-by: Laura Brehm <laurabrehm@hey.com>

cli/command/telemetry_docker.go

@@ -180,7 +180,7 @@ func toWslPath(s string) string {
 	if !ok {
 		return ""
 	}
-	return fmt.Sprintf("mnt/%s%s", drive, p)
+	return fmt.Sprintf("mnt/%s%s", strings.ToLower(drive), p)
 }
 
 func parseUNCPath(s string) (drive, p string, ok bool) {

cli/command/telemetry_docker_test.go

@@ -1,6 +1,7 @@
 package command
 
 import (
+	"io/fs"
 	"net/url"
 	"testing"
 	"testing/fstest"
@@ -9,21 +10,48 @@ import (
 )
 
 func TestWslSocketPath(t *testing.T) {
-	u, err := url.Parse("unix:////./c:/my/file/path")
+	testCases := []struct {
-	assert.NilError(t, err)
+		doc      string
+		fs       fs.FS
+		url      string
+		expected string
+	}{
+		{
+			doc: "filesystem where WSL path does not exist",
+			fs: fstest.MapFS{
+				"my/file/path": {},
+			},
+			url:      "unix:////./c:/my/file/path",
+			expected: "",
+		},
+		{
+			doc: "filesystem where WSL path exists",
+			fs: fstest.MapFS{
+				"mnt/c/my/file/path": {},
+			},
+			url:      "unix:////./c:/my/file/path",
+			expected: "/mnt/c/my/file/path",
+		},
+		{
+			doc: "filesystem where WSL path exists uppercase URL",
+			fs: fstest.MapFS{
+				"mnt/c/my/file/path": {},
+			},
+			url:      "unix:////./C:/my/file/path",
+			expected: "/mnt/c/my/file/path",
+		},
+	}
 
+	for _, tc := range testCases {
+		t.Run(tc.doc, func(t *testing.T) {
+			u, err := url.Parse(tc.url)
+			assert.NilError(t, err)
 			// Ensure host is empty.
 			assert.Equal(t, u.Host, "")
 
-	// Use a filesystem where the WSL path exists.
+			result := wslSocketPath(u.Path, tc.fs)
-	fs := fstest.MapFS{
-		"mnt/c/my/file/path": {},
-	}
-	assert.Equal(t, wslSocketPath(u.Path, fs), "/mnt/c/my/file/path")
 
-	// Use a filesystem where the WSL path doesn't exist.
+			assert.Equal(t, result, tc.expected)
-	fs = fstest.MapFS{
+		})
-		"my/file/path": {},
 	}
-	assert.Equal(t, wslSocketPath(u.Path, fs), "")
 }