[Fix] jsx-props-no-multi-spaces: Show error in multi-line props

Fixes #2223.

Author: iiison

docs/rules/jsx-props-no-multi-spaces.md

@@ -16,6 +16,13 @@ The following patterns are considered warnings:
 <App too  spacy />
 ```
 
+```jsx
+<App
+  prop1='abc'
+  
+  prop2='def' />
+```
+
 The following patterns are **not** considered warnings:
 
 ```jsx
@@ -26,6 +33,12 @@ The following patterns are **not** considered warnings:
 <App very cozy />
 ```
 
+```jsx
+<App
+  prop1='abc'
+  prop2='def' />
+```
+
 ## When Not To Use It
 
 If you are not using JSX or don't care about the space between two props in the same line.

lib/rules/jsx-props-no-multi-spaces.js

@@ -38,10 +38,22 @@ module.exports = {
     }
 
     function checkSpacing(prev, node) {
+      const prevNodeEndLine = prev.loc.end.line;
+      const currNodeStartLine = node.loc.start.line;
+
+      if (currNodeStartLine - prevNodeEndLine > 1) {
+        context.report({
+          node,
+          message: `Expected no line gap between “${getPropName(prev)}” and “${getPropName(node)}”`
+        });
+      }
+
       if (prev.loc.end.line !== node.loc.end.line) {
         return;
       }
+
       const between = context.getSourceCode().text.slice(prev.range[1], node.range[0]);
+
       if (between !== ' ') {
         context.report({
           node,

tests/lib/rules/jsx-props-no-multi-spaces.js

@@ -68,6 +68,23 @@ ruleTester.run('jsx-props-no-multi-spaces', rule, {
     code: '<Foo.Bar baz="quux" />'
   }, {
     code: '<Foobar.Foo.Bar.Baz.Qux.Quux.Quuz.Corge.Grault.Garply.Waldo.Fred.Plugh xyzzy="thud" />'
+  }, {
+    code: `
+      <button
+        title="Some button"
+        type="button"
+      />
+    `
+  }, {
+    code: `
+      <button
+        title="Some button"
+        onClick={(value) => {
+          console.log(value);
+        }}
+        type="button"
+      />
+    `
   }],
 
   invalid: [{
@@ -128,5 +145,30 @@ ruleTester.run('jsx-props-no-multi-spaces', rule, {
     errors: [
       {message: 'Expected only one space between "Foobar.Foo.Bar.Baz.Qux.Quux.Quuz.Corge.Grault.Garply.Waldo.Fred.Plugh" and "xyzzy"'}
     ]
+  }, {
+    code: `
+      <button
+        title='Some button'
+
+        type="button"
+      />
+    `,
+    errors: [{message: 'Expected no line gap between “title” and “type”'}]
+  }, {
+    code: `
+      <button
+        title="Some button"
+
+        onClick={(value) => {
+          console.log(value);
+        }}
+
+        type="button"
+      />
+    `,
+    errors: [
+      {message: 'Expected no line gap between “title” and “onClick”'},
+      {message: 'Expected no line gap between “onClick” and “type”'}
+    ]
   }]
 });