Add test for overriding a definition with MacroAnnotation without dummy definition (#19742)

Author: hamzaremmal

tests/run-macros/annot-concrete-class.check

@@ -0,0 +1 @@
+Hello, I was added by a MacroAnnotation and without being defined in the class.

tests/run-macros/annot-concrete-class/Macro_1.scala

@@ -0,0 +1,16 @@
+import scala.annotation.MacroAnnotation
+import scala.quoted.*
+
+class implementAFoo extends MacroAnnotation:
+
+    def transform(using Quotes)(tree: quotes.reflect.Definition): List[quotes.reflect.Definition] = 
+        import quotes.reflect.*
+        tree match
+            case ClassDef(name, cstr, parents, self, body) => 
+                val owner = tree.symbol
+                val sym = Symbol.newMethod(tree.symbol, "foo", ByNameType.apply(TypeRepr.of[String]))
+                val mtd = DefDef.apply(sym, _ => Some(Literal(StringConstant("Hello, I was added by a MacroAnnotation and without being defined in the class."))))
+                List(ClassDef.copy(tree)(name, cstr, parents, self, mtd :: body))
+            case _ => report.errorAndAbort(s"@implementAFoo can only be applied to classes that extend AFoo")
+        
+end implementAFoo

tests/run-macros/annot-concrete-class/Test_2.scala

@@ -0,0 +1,11 @@
+
+trait AFoo:
+    def foo: String
+
+@implementAFoo
+class Foo extends AFoo
+
+@main def Test = 
+    val foo = new Foo
+    println(foo.foo)
+