A missing enum case in a switch is a warning, not a compile-time error.

pkg/analyzer/test/generated/static_warning_code_test.dart

Index: pkg/analyzer/test/generated/static_warning_code_test.dart
diff --git a/pkg/analyzer/test/generated/static_warning_code_test.dart b/pkg/analyzer/test/generated/static_warning_code_test.dart
index eb6aa8bbd76b4c0c614b81ffc36050f4dcc7ce11..02c44b83acb0eecabfa9906b4e9d439532663205 100644
--- a/pkg/analyzer/test/generated/static_warning_code_test.dart
+++ b/pkg/analyzer/test/generated/static_warning_code_test.dart
@@ -3616,4 +3616,22 @@ class S {
     computeLibrarySourceErrors(source);
     assertErrors(source, [StaticWarningCode.VOID_RETURN_FOR_GETTER]);
   }
+
+  void test_missingEnumConstantInSwitch() {
+    Source source = addSource(r'''
+enum E { ONE, TWO, THREE, FOUR }
+bool odd(E e) {
+  switch (e) {
+    case E.ONE:
+    case E.THREE: return true;
+  }
+  return false;
+}''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [
+      StaticWarningCode.MISSING_ENUM_CONSTANT_IN_SWITCH,
+      StaticWarningCode.MISSING_ENUM_CONSTANT_IN_SWITCH
+    ]);
+    verify([source]);
+  }
 }