tests: move fixtures to dedicated dir

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I9d6ce6a264780f215b1b57d947b5264c6a6a6964

tests/fixtures/lambda_pattern.nix

@@ -0,0 +1,61 @@
+# Test lambda patterns
+let
+  # Basic destructuring
+  f1 = {
+    a,
+    b,
+  }:
+    a + b;
+
+  # With default values
+  f2 = {
+    a,
+    b ? 10,
+  }:
+    a + b;
+
+  # With ellipsis (extra fields allowed)
+  f3 = {a, ...}: a * 2;
+
+  # Named pattern with ellipsis to allow extra fields
+  f4 = arg @ {
+    a,
+    b,
+    ...
+  }:
+    a + b + arg.c;
+
+  # Simple lambda (not a pattern)
+  f5 = x: x + 1;
+in {
+  # Test basic destructuring
+  test1 = f1 {
+    a = 3;
+    b = 4;
+  };
+
+  # Test with defaults (provide both)
+  test2a = f2 {
+    a = 5;
+    b = 6;
+  };
+
+  # Test with defaults (use default for b)
+  test2b = f2 {a = 5;};
+
+  # Test ellipsis (extra field ignored)
+  test3 = f3 {
+    a = 7;
+    extra = 999;
+  };
+
+  # Test named pattern
+  test4 = f4 {
+    a = 1;
+    b = 2;
+    c = 3;
+  };
+
+  # Test simple lambda
+  test5 = f5 10;
+}