diff --git a/tests/std/include/is_permissive.hpp b/tests/std/include/is_permissive.hpp
new file mode 100644
index 00000000000..a007ec5da78
--- /dev/null
+++ b/tests/std/include/is_permissive.hpp
@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#pragma once
+
+#include <yvals_core.h>
+
+namespace detail {
+    constexpr bool permissive() {
+        return false;
+    }
+
+    template <class>
+    struct PermissiveTestBase {
+        static constexpr bool permissive() {
+            return true;
+        }
+    };
+
+    template <class T>
+    struct PermissiveTest : PermissiveTestBase<T> {
+        static constexpr bool test() {
+            return permissive();
+        }
+    };
+} // namespace detail
+
+template <class T>
+_INLINE_VAR constexpr bool is_permissive_v = detail::PermissiveTest<T>::test();
+
+_INLINE_VAR constexpr bool is_permissive = is_permissive_v<int>;
diff --git a/tests/std/include/range_algorithm_support.hpp b/tests/std/include/range_algorithm_support.hpp
index 510d3d295d2..3e69d85de3a 100644
--- a/tests/std/include/range_algorithm_support.hpp
+++ b/tests/std/include/range_algorithm_support.hpp
@@ -12,6 +12,8 @@
 #include <type_traits>
 #include <utility>
 
+#include <is_permissive.hpp>
+
 #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
 
 namespace ranges = std::ranges;
@@ -19,27 +21,6 @@ namespace ranges = std::ranges;
 template <class>
 inline constexpr bool always_false = false;
 
-namespace detail {
-    constexpr bool permissive() {
-        return false;
-    }
-
-    template <class>
-    struct DependentBase {
-        static constexpr bool permissive() {
-            return true;
-        }
-    };
-
-    template <class T>
-    struct Derived : DependentBase<T> {
-        static constexpr bool test() {
-            return permissive();
-        }
-    };
-} // namespace detail
-constexpr bool is_permissive = detail::Derived<int>::test();
-
 template <class T>
 inline constexpr T* nullptr_to = nullptr;
 
diff --git a/tests/std/include/test_mdspan_support.hpp b/tests/std/include/test_mdspan_support.hpp
index f2915e98661..de86eee8936 100644
--- a/tests/std/include/test_mdspan_support.hpp
+++ b/tests/std/include/test_mdspan_support.hpp
@@ -17,6 +17,8 @@
 #include <utility>
 #include <vector>
 
+#include <is_permissive.hpp>
+
 enum class IsExplicit : bool { no, yes };
 enum class IsNothrow : bool { no, yes };
 
@@ -173,7 +175,7 @@ constexpr bool check_accessor_policy_requirements() {
     return true;
 }
 
-namespace details {
+namespace detail {
     template <size_t... Extents, class Fn>
     constexpr void check_members_with_mixed_extents(Fn&& fn) {
         auto select_extent = [](size_t e) consteval {
@@ -221,41 +223,19 @@ namespace details {
             static_assert(sizeof...(Seq) <= 16, "We don't need more testing.");
         }
     }
-} // namespace details
+} // namespace detail
 
 template <class Fn>
 constexpr void check_members_with_various_extents(Fn&& fn) {
-    details::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<1>{});
-    details::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<2>{});
-    details::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<4>{});
-    details::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<8>{});
+    detail::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<1>{});
+    detail::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<2>{});
+    detail::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<4>{});
+    detail::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<8>{});
     if (!std::is_constant_evaluated()) {
-        details::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<16>{});
+        detail::check_members_with_various_extents_impl(std::forward<Fn>(fn), std::make_index_sequence<16>{});
     }
 }
 
-namespace details {
-    constexpr bool permissive() {
-        return false;
-    }
-
-    template <class>
-    struct PermissiveTestBase {
-        static constexpr bool permissive() {
-            return true;
-        }
-    };
-
-    template <class T>
-    struct PermissiveTest : PermissiveTestBase<T> {
-        static constexpr bool test() {
-            return permissive();
-        }
-    };
-} // namespace details
-
-inline constexpr bool is_permissive = details::PermissiveTest<int>::test();
-
 template <class Mapping>
 struct MappingProperties {
     Mapping::index_type req_span_size;
@@ -265,7 +245,7 @@ struct MappingProperties {
 };
 
 template <class Mapping>
-    requires (!details::PermissiveTest<Mapping>::test())
+    requires (!is_permissive_v<Mapping>)
 MappingProperties<Mapping> get_mapping_properties(const Mapping& mapping) {
     using IndexType     = Mapping::index_type;
     constexpr auto rank = Mapping::extents_type::rank();
@@ -327,7 +307,7 @@ MappingProperties<Mapping> get_mapping_properties(const Mapping& mapping) {
 }
 
 template <class Mapping>
-    requires (details::PermissiveTest<Mapping>::test())
+    requires (is_permissive_v<Mapping>)
 constexpr MappingProperties<Mapping> get_mapping_properties(const Mapping&) {
     return {}; // we cannot get properties in '/permissive' mode
 }
diff --git a/tests/std/tests/P0645R10_text_formatting_args/test.cpp b/tests/std/tests/P0645R10_text_formatting_args/test.cpp
index 1af863a77a2..2c02e298e3d 100644
--- a/tests/std/tests/P0645R10_text_formatting_args/test.cpp
+++ b/tests/std/tests/P0645R10_text_formatting_args/test.cpp
@@ -12,6 +12,8 @@
 #include <type_traits>
 #include <variant>
 
+#include <is_permissive.hpp>
+
 using namespace std;
 
 template <class CharType>
@@ -265,27 +267,6 @@ void test_lvalue_only_visitation() {
     visit_format_arg(lvalue_only_visitor{}, basic_format_arg<Context>{});
 }
 
-namespace detail {
-    constexpr bool permissive() {
-        return false;
-    }
-
-    template <class>
-    struct DependentBase {
-        static constexpr bool permissive() {
-            return true;
-        }
-    };
-
-    template <class T>
-    struct Derived : DependentBase<T> {
-        static constexpr bool test() {
-            return permissive();
-        }
-    };
-} // namespace detail
-constexpr bool is_permissive = detail::Derived<int>::test();
-
 template <class Context, class... Args>
 concept CanMakeFormatArgs = requires(Args&&... args) { make_format_args<Context>(static_cast<Args&&>(args)...); };
 
diff --git a/tests/std/tests/P0896R4_ranges_algorithm_machinery/test.compile.pass.cpp b/tests/std/tests/P0896R4_ranges_algorithm_machinery/test.compile.pass.cpp
index fdef67d884c..14dcb1a4479 100644
--- a/tests/std/tests/P0896R4_ranges_algorithm_machinery/test.compile.pass.cpp
+++ b/tests/std/tests/P0896R4_ranges_algorithm_machinery/test.compile.pass.cpp
@@ -11,33 +11,14 @@
 #include <type_traits>
 #include <utility>
 
+#include <is_permissive.hpp>
+
 #pragma warning(disable : 4793) // function compiled as native: non-clrcall vcall thunks must be compiled as native
 
 #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
 
 namespace ranges = std::ranges;
 
-namespace detail {
-    constexpr bool permissive() {
-        return false;
-    }
-
-    template <class>
-    struct DependentBase {
-        static constexpr bool permissive() {
-            return true;
-        }
-    };
-
-    template <class T>
-    struct Derived : DependentBase<T> {
-        static constexpr bool test() {
-            return permissive();
-        }
-    };
-} // namespace detail
-constexpr bool is_permissive = detail::Derived<int>::test();
-
 template <bool>
 struct borrowed { // borrowed<true> is a borrowed_range; borrowed<false> is not
     int* begin() const;
diff --git a/tests/std/tests/P0898R3_concepts/test.cpp b/tests/std/tests/P0898R3_concepts/test.cpp
index f8219c482bd..7a1f6a4ab60 100644
--- a/tests/std/tests/P0898R3_concepts/test.cpp
+++ b/tests/std/tests/P0898R3_concepts/test.cpp
@@ -22,6 +22,8 @@
 #include <type_traits>
 #include <utility>
 
+#include <is_permissive.hpp>
+
 #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
 
 template <class, class = void>
@@ -32,27 +34,6 @@ constexpr bool is_trait<T, std::void_t<typename T::type>> = true;
 template <class>
 constexpr bool always_false = false;
 
-namespace detail {
-    constexpr bool permissive() {
-        return false;
-    }
-
-    template <class>
-    struct DependentBase {
-        static constexpr bool permissive() {
-            return true;
-        }
-    };
-
-    template <class T>
-    struct Derived : DependentBase<T> {
-        static constexpr bool test() {
-            return permissive();
-        }
-    };
-} // namespace detail
-constexpr bool is_permissive = detail::Derived<int>::test();
-
 struct IncompleteClass;
 union IncompleteUnion;
 
diff --git a/tests/std/tests/P2136R3_invoke_r/test.cpp b/tests/std/tests/P2136R3_invoke_r/test.cpp
index 18249daed0a..5f3522b280b 100644
--- a/tests/std/tests/P2136R3_invoke_r/test.cpp
+++ b/tests/std/tests/P2136R3_invoke_r/test.cpp
@@ -6,32 +6,12 @@
 #include <string>
 #include <type_traits>
 
+#include <is_permissive.hpp>
+
 #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
 
 using namespace std;
 
-// TRANSITION, DevCom-1457457
-namespace detail {
-    constexpr bool permissive() {
-        return false;
-    }
-
-    template <class>
-    struct DependentBase {
-        static constexpr bool permissive() {
-            return true;
-        }
-    };
-
-    template <class T>
-    struct Derived : DependentBase<T> {
-        static constexpr bool test() {
-            return permissive();
-        }
-    };
-} // namespace detail
-constexpr bool is_permissive = detail::Derived<int>::test();
-
 constexpr int square(int n) {
     return n * n;
 }
diff --git a/tests/std/tests/VSO_0000000_type_traits/test.cpp b/tests/std/tests/VSO_0000000_type_traits/test.cpp
index 5791b4c618b..c42fb0372fb 100644
--- a/tests/std/tests/VSO_0000000_type_traits/test.cpp
+++ b/tests/std/tests/VSO_0000000_type_traits/test.cpp
@@ -9,6 +9,8 @@
 #include <type_traits>
 #include <utility>
 
+#include <is_permissive.hpp>
+
 using namespace std;
 
 #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
@@ -1268,27 +1270,6 @@ namespace {
     template <class T>
     constexpr bool is_trait<T, void_t<typename T::type>> = true;
 
-    namespace detail {
-        constexpr bool permissive() {
-            return false;
-        }
-
-        template <class>
-        struct DependentBase {
-            static constexpr bool permissive() {
-                return true;
-            }
-        };
-
-        template <class T>
-        struct Derived : DependentBase<T> {
-            static constexpr bool test() {
-                return permissive();
-            }
-        };
-    } // namespace detail
-    constexpr bool is_permissive = detail::Derived<int>::test();
-
     struct move_only {
         move_only()                       = default;
         move_only(move_only&&)            = default;