refactor: revert switch statement

lib/rules/prefer-read-only-props.js

@@ -12,8 +12,13 @@ const Components = require('../util/Components');
 const docsUrl = require('../util/docsUrl');
 const report = require('../util/report');
 
-const FLOW_PROPERTY_TYPE = 'ObjectTypeProperty';
-const TYPESCRIPT_PROPERTY_TYPE = 'TSPropertySignature';
+function isFlowPropertyType(node) {
+  return node.type === 'ObjectTypeProperty';
+}
+
+function isTypescriptPropertyType(node) {
+  return node.type === 'TSPropertySignature';
+}
 
 function isCovariant(node) {
   return (node.variance && node.variance.kind === 'plus')
@@ -80,12 +85,8 @@ module.exports = {
               return;
             }
 
-            switch (prop.node.type) {
-              case FLOW_PROPERTY_TYPE:
-                if (isCovariant(prop.node)) {
-                  break;
-                }
-
+            if (isFlowPropertyType(prop.node)) {
+              if (!isCovariant(prop.node)) {
                 reportReadOnlyProp(prop, propName, (fixer) => {
                   if (!prop.node.variance) {
                     // Insert covariance
@@ -95,20 +96,17 @@ module.exports = {
                   // Replace contravariance with covariance
                   return fixer.replaceText(prop.node.variance, '+');
                 });
+              }
 
-                break;
-              case TYPESCRIPT_PROPERTY_TYPE:
-                if (isReadonly(prop.node)) {
-                  break;
-                }
+              return;
+            }
 
+            if (isTypescriptPropertyType(prop.node)) {
+              if (!isReadonly(prop.node)) {
                 reportReadOnlyProp(prop, propName, (fixer) => (
                   fixer.insertTextBefore(prop.node, 'readonly ')
                 ));
-
-                break;
-              default:
-                break;
+              }
             }
           });
         });