Add acceptance test 106 showing issue with if/is implicit casting.

examples/acceptance_tests/106/lib/tests.ak

@@ -0,0 +1,62 @@
+type Foo {
+  foo: Int,
+}
+
+type Bar {
+  Buzz
+  Bazz
+}
+
+test soft_casting_1() {
+  let data: Data = Foo { foo: 42 }
+  if data is Foo {
+    True
+  } else {
+    False
+  }
+}
+
+test soft_casting_2() {
+  let data: Data = Foo { foo: 42 }
+  if data is Foo { .. }: Foo {
+    True
+  } else {
+    False
+  }
+}
+
+test soft_casting_3() {
+  let data: Data = Buzz
+  if data is Foo {
+    False
+  } else {
+    True
+  }
+}
+
+test soft_casting_4() {
+  let data: Data = Buzz
+  if data is Foo { .. }: Foo {
+    False
+  } else {
+    True
+  }
+}
+
+test soft_casting_5() {
+  let data: Data = Bazz
+  if data is Foo {
+    False
+  } else {
+    True
+  }
+}
+
+test soft_casting_6() {
+  let data: Data = Bazz
+  if data is Foo { .. }: Foo {
+    False
+  } else {
+    True
+  }
+}