diff --git a/var/spack/repos/builtin.mock/packages/zlib-ng/package.py b/var/spack/repos/builtin.mock/packages/zlib-ng/package.py
new file mode 100644
index 00000000000..023de5d782d
--- /dev/null
+++ b/var/spack/repos/builtin.mock/packages/zlib-ng/package.py
@@ -0,0 +1,106 @@
+# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.build_systems import autotools, cmake
+from spack.package import *
+
+
+class ZlibNg(AutotoolsPackage, CMakePackage):
+    """
+    zlib replacement with optimizations for next generation systems.
+    -- added to the mock packages for GitVersion re-use testing, but
+       removed patches
+    """
+
+    homepage = "https://github.com/zlib-ng/zlib-ng"
+    url = "https://github.com/zlib-ng/zlib-ng/archive/2.0.0.tar.gz"
+    git = "https://github.com/zlib-ng/zlib-ng.git"
+
+    maintainers("haampie")
+
+    license("Zlib")
+
+    version("2.1.6", sha256="a5d504c0d52e2e2721e7e7d86988dec2e290d723ced2307145dedd06aeb6fef2")
+    version("2.1.5", sha256="3f6576971397b379d4205ae5451ff5a68edf6c103b2f03c4188ed7075fbb5f04")
+    version("2.1.4", sha256="a0293475e6a44a3f6c045229fe50f69dc0eebc62a42405a51f19d46a5541e77a")
+    version(
+        "2.1.3",
+        sha256="d20e55f89d71991c59f1c5ad1ef944815e5850526c0d9cd8e504eaed5b24491a",
+        deprecated=True,
+    )
+    version(
+        "2.1.2",
+        sha256="383560d6b00697c04e8878e26c0187b480971a8bce90ffd26a5a7b0f7ecf1a33",
+        deprecated=True,
+    )
+    version("2.0.7", sha256="6c0853bb27738b811f2b4d4af095323c3d5ce36ceed6b50e5f773204fb8f7200")
+    version("2.0.0", sha256="86993903527d9b12fc543335c19c1d33a93797b3d4d37648b5addae83679ecd8")
+
+    variant("compat", default=True, description="Enable compatibility API")
+    variant("opt", default=True, description="Enable optimizations")
+    variant("shared", default=True, description="Build shared library")
+    variant("pic", default=True, description="Enable position-independent code (PIC)")
+
+    conflicts("+shared~pic")
+
+    variant("new_strategies", default=True, description="Enable new deflate strategies")
+
+    provides("zlib-api", when="+compat")
+
+    # Default to autotools, since cmake would result in circular dependencies if it's not
+    # reused.
+    build_system("autotools", "cmake", default="autotools")
+
+    with when("build_system=cmake"):
+        depends_on("cmake@3.5.1:", type="build")
+        depends_on("cmake@3.14.0:", type="build", when="@2.1.0:")
+
+    conflicts("%nvhpc@:20", msg="the compiler is too old and too broken")
+
+    @property
+    def libs(self):
+        name = "libz" if self.spec.satisfies("+compat") else "libz-ng"
+        return find_libraries(
+            name, root=self.prefix, recursive=True, shared=self.spec.satisfies("+shared")
+        )
+
+    def flag_handler(self, name, flags):
+        if name == "cflags" and self.spec.satisfies("+pic build_system=autotools"):
+            flags.append(self.compiler.cc_pic_flag)
+        return (flags, None, None)
+
+
+class AutotoolsBuilder(autotools.AutotoolsBuilder):
+
+    @run_before("configure")
+    def pretend_gcc(self):
+        # All nice things (PIC flags, symbol versioning) that happen to the compilers that are
+        # recognized as gcc (%gcc, %clang, %intel, %oneapi) we want for some other compilers too:
+        if self.spec.compiler.name in ["nvhpc"]:
+            filter_file(r"^gcc=0$", "gcc=1", join_path(self.configure_directory, "configure"))
+
+    def configure_args(self):
+        args = []
+        if self.spec.satisfies("+compat"):
+            args.append("--zlib-compat")
+        if self.spec.satisfies("~opt"):
+            args.append("--without-optimizations")
+        if self.spec.satisfies("~shared"):
+            args.append("--static")
+        if self.spec.satisfies("~new_strategies"):
+            args.append("--without-new-strategies")
+        return args
+
+
+class CMakeBuilder(cmake.CMakeBuilder):
+    def cmake_args(self):
+        return [
+            self.define_from_variant("ZLIB_COMPAT", "compat"),
+            self.define_from_variant("WITH_OPTIM", "opt"),
+            self.define("BUILD_SHARED_LIBS", self.spec.satisfies("+shared")),
+            self.define_from_variant("CMAKE_POSITION_INDEPENDENT_CODE", "pic"),
+            self.define_from_variant("WITH_NEW_STRATEGIES", "new_strategies"),
+            self.define("ZLIB_ENABLE_TESTS", self.pkg.run_tests),
+        ]