diff --git a/repos/spack_repo/builtin/packages/tts/package.py b/repos/spack_repo/builtin/packages/tts/package.py
new file mode 100644
index 00000000000..790f2e9aad4
--- /dev/null
+++ b/repos/spack_repo/builtin/packages/tts/package.py
@@ -0,0 +1,43 @@
+# Copyright Spack Project Developers. See COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack_repo.builtin.build_systems.cmake import CMakePackage
+
+from spack.package import *
+
+
+class Tts(CMakePackage):
+    """TTS - Tiny Test System, a C++20 unit test library for numerical code."""
+
+    homepage = "https://jfalcou.github.io/tts/"
+    url = "https://github.com/jfalcou/tts/archive/refs/tags/3.0.tar.gz"
+    git = "https://github.com/jfalcou/tts.git"
+
+    maintainers("jfalcou")
+
+    license("BSL-1.0")
+
+    version("main", branch="main")
+    version("3.0", sha256="3954fb40a2d444bc935ecf2d439ed72d3c72eae9ec1b021fc99b469166bf57cd")
+
+    depends_on("cxx", type="build")
+    depends_on("cmake@3.22:", type="build")
+    # The build is written with copacabana, which CPM fetches at configure time; the
+    # prefix installed here is handed to CPM instead, see cmake_args.
+    depends_on("copacabana", type="build")
+
+    def cmake_args(self):
+        return [
+            self.define("CPM_COPACABANA_SOURCE", self.spec["copacabana"].prefix),
+            self.define("CPM_LOCAL_PACKAGES_ONLY", True),
+            self.define("TTS_BUILD_TEST", self.run_tests),
+            self.define("TTS_BUILD_DOCUMENTATION", False),
+        ]
+
+    def check(self):
+        # `all` builds nothing in a header-only library; the unit tests hang off the
+        # aggregate target copacabana defines for the project.
+        with working_dir(self.build_directory):
+            cmake("--build", ".", "--target", "tts-test", "--parallel", str(make_jobs))
+            ctest("--output-on-failure", "--parallel", str(make_jobs))