fix: membership infering for methods (#1122)

* Fix membership infering for methods

Improve inferMembership to allow to use next code:
```js
/**
 * @memberof BigFeature
 */
class MyClass {
  method() {}
}
```
Before this improvement, we have `method` inside
 `global.MyClass` instead of `global.BigFeature.MyClass`

* Add tests fir membership infering for methods

__tests__/lib/infer/membership.js

@@ -276,6 +276,38 @@ test('inferMembership - explicit', function() {
     scope: 'instance'
   });
 
+  expect(
+    pick(
+      evaluate(function() {
+        /** @memberof bar */
+        class Foo {
+          /** */
+          baz() {}
+        }
+      })[1], // [0] is an description for class Foo
+      ['memberof', 'scope']
+    )
+  ).toEqual({
+    memberof: 'bar.Foo',
+    scope: 'instance'
+  });
+
+  expect(
+    pick(
+      evaluate(function() {
+        /** @memberof bar */
+        class Foo {
+          /** */
+          static baz() {}
+        }
+      })[1], // [0] is an description for class Foo
+      ['memberof', 'scope']
+    )
+  ).toEqual({
+    memberof: 'bar.Foo',
+    scope: 'static'
+  });
+
   expect(
     pick(
       evaluate(function() {

src/infer/membership.js

@@ -39,6 +39,33 @@ function findLendsIdentifiers(path) {
   }
 }
 
+/**
+ * Given an AST node, try to find a comment before the class declaration that
+ * has a `memberof` tag, and if it has that, return the tag, split by
+ * .s with the name of the class.
+ *
+ * @private
+ * @param {Object} path AST node
+ * @returns {Array<string>} class membership
+ */
+function inferClassMembership(path) {
+  if (path.get('leadingComments')) {
+    const leadingComments = path.get('leadingComments');
+
+    for (let i = leadingComments.length - 1; i >= 0; i--) {
+      const comment = leadingComments[i];
+      if (isJSDocComment(comment.node)) {
+        const memberof = parse(comment.node.value).memberof;
+        if (memberof) {
+          return [...memberof.split('.'), path.node.id.name];
+        }
+      }
+    }
+  }
+
+  return [path.node.id.name];
+}
+
 /**
  * Extract and return the identifiers for expressions of
  * type this.foo
@@ -347,7 +374,7 @@ module.exports = function() {
 
       return inferMembershipFromIdentifiers(
         comment,
-        [declarationNode.id.name],
+        inferClassMembership(path.parentPath.parentPath),
         scope
       );
     }