diff --git a/compiler/testData/diagnostics/tests/DiamondFunction.jet b/compiler/testData/diagnostics/tests/DiamondFunction.jet
new file mode 100644
index 00000000000..b22834a1978
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DiamondFunction.jet
@@ -0,0 +1,9 @@
+open class Base() {
+    fun f() = 1
+}
+    
+open class Left() : Base()
+
+trait Right : Base
+
+class Diamond() : Left(), Right
diff --git a/compiler/testData/diagnostics/tests/DiamondProperty.jet b/compiler/testData/diagnostics/tests/DiamondProperty.jet
new file mode 100644
index 00000000000..0f6099b0bf9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DiamondProperty.jet
@@ -0,0 +1,10 @@
+
+open class Base() {
+    var v : Int = 0
+}
+    
+open class Left() : Base()
+
+trait Right : Base
+
+class Diamond() : Left(), Right