diff --git a/tests/SwaggerProvider.Tests/CachingTests.fs b/tests/SwaggerProvider.Tests/CachingTests.fs
new file mode 100644
index 00000000..85bc4362
--- /dev/null
+++ b/tests/SwaggerProvider.Tests/CachingTests.fs
@@ -0,0 +1,111 @@
+namespace SwaggerProvider.Tests.CachingTests
+
+open System
+open System.Threading
+open Xunit
+open FsUnitTyped
+open SwaggerProvider.Caching
+
+/// Unit tests for the in-memory ICache implementation used by Provider.OpenApiClient.fs
+/// to cache generated provided types keyed by schema/parameter combination.
+module InMemoryCacheTests =
+
+    [<Fact>]
+    let ``TryRetrieve returns None for a key that was never set``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        cache.TryRetrieve("missing") |> shouldEqual None
+
+    [<Fact>]
+    let ``Set followed by TryRetrieve returns the stored value``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        cache.Set("key1", 42)
+        cache.TryRetrieve("key1") |> shouldEqual(Some 42)
+
+    [<Fact>]
+    let ``Set overwrites a previously stored value for the same key``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        cache.Set("key1", "first")
+        cache.Set("key1", "second")
+        cache.TryRetrieve("key1") |> shouldEqual(Some "second")
+
+    [<Fact>]
+    let ``Remove deletes a stored value so TryRetrieve returns None``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        cache.Set("key1", 1)
+        cache.Remove("key1")
+        cache.TryRetrieve("key1") |> shouldEqual None
+
+    [<Fact>]
+    let ``Remove on a missing key does not throw``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        // Should be a no-op, not an exception.
+        cache.Remove("never-set")
+
+    [<Fact>]
+    let ``GetOrAdd calls the factory once and returns its result on first access``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        let mutable calls = 0
+
+        let result =
+            cache.GetOrAdd(
+                "key1",
+                fun () ->
+                    calls <- calls + 1
+                    "computed"
+            )
+
+        result |> shouldEqual "computed"
+        calls |> shouldEqual 1
+
+    [<Fact>]
+    let ``GetOrAdd does not call the factory again once the value is cached``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        let mutable calls = 0
+
+        let factory() =
+            calls <- calls + 1
+            calls
+
+        cache.GetOrAdd("key1", factory) |> shouldEqual 1
+        // Second call should return the same cached value (1), not invoke the factory again (which would return 2).
+        cache.GetOrAdd("key1", factory) |> shouldEqual 1
+        calls |> shouldEqual 1
+
+    [<Fact>]
+    let ``GetOrAdd with different keys caches values independently``() =
+        let cache = createInMemoryCache(TimeSpan.FromMinutes 5.0)
+        cache.GetOrAdd("a", fun () -> "value-a") |> shouldEqual "value-a"
+        cache.GetOrAdd("b", fun () -> "value-b") |> shouldEqual "value-b"
+        cache.TryRetrieve("a") |> shouldEqual(Some "value-a")
+        cache.TryRetrieve("b") |> shouldEqual(Some "value-b")
+
+    [<Fact>]
+    let ``TryRetrieve returns None once the expiration window has elapsed``() =
+        let cache = createInMemoryCache(TimeSpan.FromMilliseconds 20.0)
+        cache.Set("key1", "value")
+        Thread.Sleep(200)
+        cache.TryRetrieve("key1") |> shouldEqual None
+
+    [<Fact>]
+    let ``TryRetrieve with extendCacheExpiration=true keeps the entry alive past the original expiration``() =
+        let cache = createInMemoryCache(TimeSpan.FromMilliseconds 500.0)
+        cache.Set("key1", "value")
+        // Read partway through the window and extend the expiration.
+        Thread.Sleep(200)
+
+        cache.TryRetrieve("key1", extendCacheExpiration = true)
+        |> shouldEqual(Some "value")
+        // Total elapsed time (200 + 350 = 550ms) exceeds the original 500ms window,
+        // but the extension at 200ms should have reset the clock, so it should still be present.
+        Thread.Sleep(350)
+        cache.TryRetrieve("key1") |> shouldEqual(Some "value")
+
+    [<Fact>]
+    let ``TryRetrieve without extendCacheExpiration does not reset expiration``() =
+        let cache = createInMemoryCache(TimeSpan.FromMilliseconds 100.0)
+        cache.Set("key1", "value")
+        Thread.Sleep(60)
+        cache.TryRetrieve("key1") |> shouldEqual(Some "value")
+        Thread.Sleep(80)
+        // Original 100ms window has elapsed (60 + 80 = 140ms) without extension.
+        cache.TryRetrieve("key1") |> shouldEqual None
diff --git a/tests/SwaggerProvider.Tests/SwaggerProvider.Tests.fsproj b/tests/SwaggerProvider.Tests/SwaggerProvider.Tests.fsproj
index e039d519..d878d6de 100644
--- a/tests/SwaggerProvider.Tests/SwaggerProvider.Tests.fsproj
+++ b/tests/SwaggerProvider.Tests/SwaggerProvider.Tests.fsproj
@@ -24,6 +24,7 @@
     <Compile Include="SsrfSecurityTests.fs" />
     <Compile Include="RuntimeHelpersTests.fs" />
     <Compile Include="UtilsTests.fs" />
+    <Compile Include="CachingTests.fs" />
     <None Include="paket.references" />
     <ProjectReference Include="..\..\src\SwaggerProvider.DesignTime\SwaggerProvider.DesignTime.fsproj" />
   </ItemGroup>