feat: Add excludeVariableTypes option to require-variable-type

Enable ignoring all var, let, or const independently

.README/rules/require-variable-type.md

@@ -23,4 +23,28 @@ The default pattern is `a^`, which doesn't match anything, i.e., all parameters
 ```
 
 
+You can choose specific variable types (`var`, `let`, and `const`) to ignore using `excludeVariableTypes`.
+
+This excludes `var` and `let` declarations from needing type annotations, but forces `const` declarations to have it.
+By default, all declarations are checked.
+
+```js
+{
+    "rules": {
+        "flowtype/require-variable-type": [
+            2,
+            {
+              "excludeVariableTypes": {
+                "var": true,
+                "let": true,
+                "const": false,
+              }
+            }
+        ]
+    }
+}
+```
+
+
+
 <!-- assertions requireVariableType -->

src/rules/requireVariableType.js

@@ -12,9 +12,16 @@ export default (context) => {
   }
 
   const excludeVariableMatch = new RegExp(_.get(context, 'options[0].excludeVariableMatch', 'a^'));
+  const excludeVariableTypes = _.get(context, 'options[0].excludeVariableTypes', {});
 
   return {
     VariableDeclaration: (variableDeclaration) => {
+      const variableType = _.get(variableDeclaration, 'kind');
+
+      if (_.get(excludeVariableTypes, variableType)) {
+        return;
+      }
+
       _.forEach(variableDeclaration.declarations, (variableDeclarator) => {
         const identifierNode = _.get(variableDeclarator, 'id');
         const identifierName = _.get(identifierNode, 'name');

tests/rules/assertions/requireVariableType.js

@@ -28,6 +28,22 @@ export default {
           excludeVariableMatch: '^_'
         }
       ]
+    },
+    {
+      code: 'var foo = "bar", bar = 1; const oob : string = "oob"; let hey = "yah"',
+      errors: [
+        {
+          message: 'Missing "hey" variable type annotation.'
+        }
+      ],
+      options: [
+        {
+          excludeVariableTypes: {
+            let: false,
+            var: true
+          }
+        }
+      ]
     }
   ],
   valid: [
@@ -44,6 +60,27 @@ export default {
           excludeVariableMatch: '^_'
         }
       ]
+    },
+    {
+      code: 'var foo = "bar", bar = 1',
+      options: [
+        {
+          excludeVariableTypes: {
+            var: true
+          }
+        }
+      ]
+    },
+    {
+      code: 'var foo = "bar", bar = 1; const oob : string = "oob"; let hey = "yah"',
+      options: [
+        {
+          excludeVariableTypes: {
+            let: true,
+            var: true
+          }
+        }
+      ]
     }
   ]
 };