Fix multiple reporting of same warnings in vue/no-unregistered-component (#1382)

* fix multiple reporting of unregistered components

* add tests

* fix linter error

Author: enzo360

lib/rules/no-unregistered-components.js

@@ -126,7 +126,7 @@ module.exports = {
           usedComponentNodes.push({ node, name: node.value.value })
         },
         /** @param {VElement} node */
-        "VElement[name='template']:exit"() {
+        "VElement[name='template'][parent.type='VDocumentFragment']:exit"() {
           // All registered components, transformed to kebab-case
           const registeredComponentNames = registeredComponents.map(
             ({ name }) => casing.kebabCase(name)

tests/lib/rules/no-unregistered-components.js

@@ -458,6 +458,25 @@ tester.run('no-unregistered-components', rule, {
         }
         </script>
       `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        <template>
+          <CustomComponentWithNamedSlots>
+            <template #slotA>
+              <div>Text</div>
+            </template>
+          </CustomComponentWithNamedSlots>
+        </template>
+        <script>
+        export default {
+          components: {
+            CustomComponentWithNamedSlots
+          }
+        }
+        </script>
+      `
     }
   ],
   invalid: [
@@ -668,6 +687,25 @@ tester.run('no-unregistered-components', rule, {
           line: 3
         }
       ]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        <template>
+          <CustomComponentWithNamedSlots>
+            <template #slotA>
+              <div>Text</div>
+            </template>
+          </CustomComponentWithNamedSlots>
+        </template>
+      `,
+      errors: [
+        {
+          message:
+            'The "CustomComponentWithNamedSlots" component has been used but not registered.',
+          line: 3
+        }
+      ]
     }
   ]
 })