diff --git a/tools/src/cmd/cts/common/gen_test_list.go b/tools/src/cmd/cts/common/gen_test_list.go
new file mode 100644
index 0000000..68226c4
--- /dev/null
+++ b/tools/src/cmd/cts/common/gen_test_list.go
@@ -0,0 +1,42 @@
+package common
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+// GenTestList queries the CTS for the newline delimited list of test names
+func GenTestList(ctx context.Context, ctsDir, node string) (string, error) {
+	// Run 'src/common/runtime/cmdline.ts' to obtain the full test list
+	cmd := exec.CommandContext(ctx, node,
+		"-e", "require('./src/common/tools/setup-ts-in-node.js');require('./src/common/runtime/cmdline.ts');",
+		"--", // Start of arguments
+		// src/common/runtime/helper/sys.ts expects 'node file.js <args>'
+		// and slices away the first two arguments. When running with '-e', args
+		// start at 1, so just inject a placeholder argument.
+		"placeholder-arg",
+		"--list",
+		"webgpu:*",
+	)
+	cmd.Dir = ctsDir
+
+	stderr := bytes.Buffer{}
+	cmd.Stderr = &stderr
+
+	out, err := cmd.Output()
+	if err != nil {
+		return "", fmt.Errorf("failed to generate test list: %w\n%v", err, stderr.String())
+	}
+
+	tests := []string{}
+	for _, test := range strings.Split(string(out), "\n") {
+		if test != "" {
+			tests = append(tests, test)
+		}
+	}
+
+	return strings.Join(tests, "\n"), nil
+}
diff --git a/tools/src/cmd/cts/common/paths.go b/tools/src/cmd/cts/common/paths.go
index 3cbe03d..17d1bb7 100644
--- a/tools/src/cmd/cts/common/paths.go
+++ b/tools/src/cmd/cts/common/paths.go
@@ -47,9 +47,11 @@
 	// slow_tests.txt file.
 	RelativeSlowExpectationsPath = "webgpu-cts/slow_tests.txt"
 
-	// RelativeTestListPath is the dawn-root relative path to the
-	// test_list.txt file.
+	// RelativeTestListPath is the dawn-root relative path to the test_list.txt file.
 	RelativeTestListPath = "third_party/gn/webgpu-cts/test_list.txt"
+
+	// RelativeCTSPath is the dawn-root relative path to the WebGPU CTS directory.
+	RelativeCTSPath = "third_party/webgpu-cts"
 )
 
 // DefaultExpectationsPath returns the default path to the expectations.txt
@@ -91,8 +93,8 @@
 	return path
 }
 
-// DefaultTestListPath returns the default path to the test_list.txt
-// file. Returns an empty string if the file cannot be found.
+// DefaultTestListPath returns the default path to the test_list.txt file.
+// Returns an empty string if the file cannot be found.
 func DefaultTestListPath() string {
 	path := filepath.Join(fileutils.DawnRoot(), RelativeTestListPath)
 	if _, err := os.Stat(path); err != nil {
@@ -100,3 +102,13 @@
 	}
 	return path
 }
+
+// DefaultCTSPath returns the default path to the WenGPU CTS directory.
+// Returns an empty string if the file cannot be found.
+func DefaultCTSPath() string {
+	path := filepath.Join(fileutils.DawnRoot(), RelativeCTSPath)
+	if _, err := os.Stat(path); err != nil {
+		return ""
+	}
+	return path
+}
diff --git a/tools/src/cmd/cts/main.go b/tools/src/cmd/cts/main.go
index b8e4f77..8b4f01c 100644
--- a/tools/src/cmd/cts/main.go
+++ b/tools/src/cmd/cts/main.go
@@ -48,7 +48,8 @@
 	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/roll"
 	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/time"
 	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/treemap"
-	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/update"
+	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/update/expectations"
+	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/update/testlist"
 	_ "dawn.googlesource.com/dawn/tools/src/cmd/cts/validate"
 )
 
diff --git a/tools/src/cmd/cts/roll/roll.go b/tools/src/cmd/cts/roll/roll.go
index bc85448..f1e0734 100644
--- a/tools/src/cmd/cts/roll/roll.go
+++ b/tools/src/cmd/cts/roll/roll.go
@@ -28,7 +28,6 @@
 package roll
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"flag"
@@ -809,35 +808,7 @@
 
 // genTestList returns the newline delimited list of test names, for the CTS checkout at r.ctsDir
 func (r *roller) genTestList(ctx context.Context) (string, error) {
-	// Run 'src/common/runtime/cmdline.ts' to obtain the full test list
-	cmd := exec.CommandContext(ctx, r.flags.nodePath,
-		"-e", "require('./src/common/tools/setup-ts-in-node.js');require('./src/common/runtime/cmdline.ts');",
-		"--", // Start of arguments
-		// src/common/runtime/helper/sys.ts expects 'node file.js <args>'
-		// and slices away the first two arguments. When running with '-e', args
-		// start at 1, so just inject a placeholder argument.
-		"placeholder-arg",
-		"--list",
-		"webgpu:*",
-	)
-	cmd.Dir = r.ctsDir
-
-	stderr := bytes.Buffer{}
-	cmd.Stderr = &stderr
-
-	out, err := cmd.Output()
-	if err != nil {
-		return "", fmt.Errorf("failed to generate test list: %w\n%v", err, stderr.String())
-	}
-
-	tests := []string{}
-	for _, test := range strings.Split(string(out), "\n") {
-		if test != "" {
-			tests = append(tests, test)
-		}
-	}
-
-	return strings.Join(tests, "\n"), nil
+	return common.GenTestList(ctx, r.ctsDir, r.flags.nodePath)
 }
 
 // genResourceFilesList returns a list of resource files, for the CTS checkout at r.ctsDir
diff --git a/tools/src/cmd/cts/treemap/treemap.go b/tools/src/cmd/cts/treemap/treemap.go
index ff93e6c..a6f4b8b 100644
--- a/tools/src/cmd/cts/treemap/treemap.go
+++ b/tools/src/cmd/cts/treemap/treemap.go
@@ -155,17 +155,13 @@
 
 // loadCasesData creates the JSON payload for a cases visualization
 func loadCasesData() (string, error) {
-	testListPath := filepath.Join(fileutils.DawnRoot(), common.TestListRelPath)
-
-	file, err := os.Open(testListPath)
+	testlist, err := common.GenTestList(context.Background(), common.DefaultCTSPath(), fileutils.NodePath())
 	if err != nil {
-		return "", fmt.Errorf("failed to open test list: %w", err)
+		return "", err
 	}
-	defer file.Close()
-
 	queryCounts := container.NewMap[string, int]()
 
-	scanner := bufio.NewScanner(file)
+	scanner := bufio.NewScanner(strings.NewReader(testlist))
 	for scanner.Scan() {
 		if name := strings.TrimSpace(scanner.Text()); name != "" {
 			q := query.Parse(name)
@@ -184,7 +180,7 @@
 	data := &strings.Builder{}
 	fmt.Fprint(data, `{`)
 	fmt.Fprint(data, `"desc":"Treemap visualization of the CTS test cases.<br>Area represents total number of test cases.<br>Color represents the number of parameterized test cases for a single test.",`)
-	fmt.Fprint(data, `"limit": 5000,`)
+	fmt.Fprintf(data, `"limit": 1000,`)
 	fmt.Fprint(data, `"data":[`)
 	fmt.Fprint(data, `["Query", "Parent", "Number of tests", "Color"],`)
 	fmt.Fprint(data, `["root", null, 0, 0]`)
diff --git a/tools/src/cmd/cts/update/update.go b/tools/src/cmd/cts/update/expectations/expectations.go
similarity index 98%
rename from tools/src/cmd/cts/update/update.go
rename to tools/src/cmd/cts/update/expectations/expectations.go
index ea3b4fe..1bbf024 100644
--- a/tools/src/cmd/cts/update/update.go
+++ b/tools/src/cmd/cts/update/expectations/expectations.go
@@ -25,7 +25,7 @@
 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-package update
+package expectations
 
 import (
 	"context"
@@ -68,7 +68,7 @@
 }
 
 func (cmd) Name() string {
-	return "update"
+	return "update-expectations"
 }
 
 func (cmd) Desc() string {
diff --git a/tools/src/cmd/cts/update/testlist/testlist.go b/tools/src/cmd/cts/update/testlist/testlist.go
new file mode 100644
index 0000000..395b133
--- /dev/null
+++ b/tools/src/cmd/cts/update/testlist/testlist.go
@@ -0,0 +1,85 @@
+// Copyright 2022 The Dawn & Tint Authors
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this
+//    list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its
+//    contributors may be used to endorse or promote products derived from
+//    this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package testlist
+
+import (
+	"context"
+	"flag"
+	"os"
+	"strings"
+
+	"dawn.googlesource.com/dawn/tools/src/cmd/cts/common"
+	"dawn.googlesource.com/dawn/tools/src/fileutils"
+)
+
+func init() {
+	common.Register(&cmd{})
+}
+
+type arrayFlags []string
+
+func (i *arrayFlags) String() string {
+	return strings.Join((*i), " ")
+}
+
+func (i *arrayFlags) Set(value string) error {
+	*i = append(*i, value)
+	return nil
+}
+
+type cmd struct {
+	flags struct {
+		ctsDir   string
+		nodePath string
+		output   string
+	}
+}
+
+func (cmd) Name() string {
+	return "update-testlist"
+}
+
+func (cmd) Desc() string {
+	return "updates a CTS expectations file"
+}
+
+func (c *cmd) RegisterFlags(ctx context.Context, cfg common.Config) ([]string, error) {
+	flag.StringVar(&c.flags.ctsDir, "cts", common.DefaultCTSPath(), "path to the CTS")
+	flag.StringVar(&c.flags.nodePath, "node", fileutils.NodePath(), "path to node")
+	flag.StringVar(&c.flags.output, "out", common.DefaultTestListPath(), "output testlist path")
+	return nil, nil
+}
+
+func (c *cmd) Run(ctx context.Context, cfg common.Config) error {
+	list, err := common.GenTestList(ctx, c.flags.ctsDir, c.flags.nodePath)
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(c.flags.output, []byte(list), 0666)
+}