diff --git a/ts/deckconfig/BUILD.bazel b/ts/deckconfig/BUILD.bazel
index 7a5d4828b..906fb074b 100644
--- a/ts/deckconfig/BUILD.bazel
+++ b/ts/deckconfig/BUILD.bazel
@@ -5,7 +5,7 @@ load("//ts/svelte:svelte.bzl", "compile_svelte", "svelte", "svelte_check")
 load("//ts:esbuild.bzl", "esbuild")
 load("//ts:vendor.bzl", "copy_bootstrap_icons")
 load("//ts:compile_sass.bzl", "compile_sass")
-load("@npm//jest-cli:index.bzl", "jest_test")
+load("//ts:jest.bzl", "jest_test")
 
 compile_sass(
     srcs = ["deckconfig-base.scss"],
@@ -125,35 +125,12 @@ svelte_check(
     ],
 )
 
-ts_library(
-    name = "test_lib",
-    srcs = glob(["*.test.ts"]),
-    tsconfig = "//ts:tsconfig.json",
+jest_test(
+    data = [
+        "@npm//protobufjs",
+    ],
     deps = [
         ":lib",
         "//ts/lib:backend_proto",
-        "@npm//@types/jest",
     ],
 )
-
-jest_test(
-    name = "test",
-    args = [
-        "--no-cache",
-        "--no-watchman",
-        "--ci",
-        "--colors",
-        "--config",
-        "$(location //ts:jest.config.js)",
-    ],
-    data = [
-        ":test_lib",
-        "//ts:jest.config.js",
-        "@npm//protobufjs",
-    ],
-    target_compatible_with = select({
-        "@platforms//os:osx": [],
-        "@platforms//os:linux": [],
-        "//conditions:default": ["@platforms//os:linux"],
-    }),
-)
diff --git a/ts/html-filter/BUILD.bazel b/ts/html-filter/BUILD.bazel
index 711424e90..d4fed4512 100644
--- a/ts/html-filter/BUILD.bazel
+++ b/ts/html-filter/BUILD.bazel
@@ -1,5 +1,5 @@
 load("@npm//@bazel/typescript:index.bzl", "ts_library")
-load("@npm//jest-cli:index.bzl", "jest_test")
+load("//ts:jest.bzl", "jest_test")
 load("//ts:prettier.bzl", "prettier_test")
 load("//ts:eslint.bzl", "eslint_test")
 
@@ -15,38 +15,12 @@ ts_library(
     deps = [],
 )
 
-ts_library(
-    name = "test_lib",
-    srcs = glob(["*.test.ts"]),
-    tsconfig = "//ts:tsconfig.json",
+jest_test(
     deps = [
         "html-filter",
-        "@npm//@types/jest",
     ],
 )
 
-jest_test(
-    name = "test",
-    args = [
-        "--no-cache",
-        "--no-watchman",
-        "--ci",
-        "--colors",
-        "--config",
-        "$(location //ts:jest.config.js)",
-    ],
-    data = [
-        ":test_lib",
-        "//ts:jest.config.js",
-        "//ts:package.json",
-    ],
-    target_compatible_with = select({
-        "@platforms//os:osx": [],
-        "@platforms//os:linux": [],
-        "//conditions:default": ["@platforms//os:linux"],
-    }),
-)
-
 # Tests
 ################
 
diff --git a/ts/jest.bzl b/ts/jest.bzl
new file mode 100644
index 000000000..5bb05b010
--- /dev/null
+++ b/ts/jest.bzl
@@ -0,0 +1,37 @@
+load("@npm//@bazel/typescript:index.bzl", "ts_library")
+load("@npm//jest-cli:index.bzl", _jest_test = "jest_test")
+
+def jest_test(deps, data = [], name = "jest"):
+    "Build *.test.ts into a library, then test it with Jest."
+
+    # compile sources
+    ts_library(
+        name = name + "_lib",
+        srcs = native.glob(["*.test.ts"]),
+        tsconfig = "//ts:tsconfig.json",
+        deps = deps + [
+            "@npm//@types/jest",
+        ],
+    )
+
+    # then test them
+    _jest_test(
+        name = name,
+        args = [
+            "--no-cache",
+            "--no-watchman",
+            "--ci",
+            "--colors",
+            "--config",
+            "$(location //ts:jest.config.js)",
+        ],
+        data = data + [
+            name + "_lib",
+            "//ts:jest.config.js",
+        ],
+        target_compatible_with = select({
+            "@platforms//os:osx": [],
+            "@platforms//os:linux": [],
+            "//conditions:default": ["@platforms//os:linux"],
+        }),
+    )
diff --git a/ts/lib/BUILD.bazel b/ts/lib/BUILD.bazel
index d5bb24e1a..01d538429 100644
--- a/ts/lib/BUILD.bazel
+++ b/ts/lib/BUILD.bazel
@@ -2,7 +2,7 @@ load("@npm//@bazel/typescript:index.bzl", "ts_library")
 load("//ts:prettier.bzl", "prettier_test")
 load("//ts:eslint.bzl", "eslint_test")
 load("//ts:protobuf.bzl", "protobufjs_library")
-load("@npm//jest-cli:index.bzl", "jest_test")
+load("//ts:jest.bzl", "jest_test")
 
 # Protobuf
 #############
@@ -77,34 +77,11 @@ eslint_test(
     srcs = glob(["*.ts"]),
 )
 
-ts_library(
-    name = "test_lib",
-    srcs = glob(["*.test.ts"]),
-    tsconfig = "//ts:tsconfig.json",
-    deps = [
-        ":lib",
-        "@npm//@types/jest",
-    ],
-)
-
 jest_test(
-    name = "test",
-    args = [
-        "--no-cache",
-        "--no-watchman",
-        "--ci",
-        "--colors",
-        "--config",
-        "$(location //ts:jest.config.js)",
-    ],
     data = [
-        ":test_lib",
-        "//ts:jest.config.js",
         "@npm//protobufjs",
     ],
-    target_compatible_with = select({
-        "@platforms//os:osx": [],
-        "@platforms//os:linux": [],
-        "//conditions:default": ["@platforms//os:linux"],
-    }),
+    deps = [
+        ":lib",
+    ],
 )