fix(require-returns-check): allow infinite loops to only have one branch return; fixes #932

Author: brettz9

README.md

@@ -17881,6 +17881,20 @@ function foo() {
     }
 };
 // Message: JSDoc @returns declaration present but return expression not available in function.
+
+/**
+ * @returns {number}
+ */
+function foo() {
+  let n = 1;
+  while (n > 0.5) {
+    n = Math.random();
+    if (n < 0.2) {
+      return n;
+    }
+  }
+}
+// Message: JSDoc @returns declaration present but return expression not available in function.
 ````
 
 The following patterns are not considered problems:
@@ -18517,6 +18531,18 @@ const quux = (someVar) => {
     return true;
   }
 };
+
+/**
+ * @returns {number}
+ */
+function foo() {
+  while (true) {
+    const n = Math.random();
+    if (n < 0.5) {
+      return n;
+    }
+  }
+}
 ````
 
 

src/utils/hasReturnValue.js

@@ -149,9 +149,16 @@ const allBrancheshaveReturnValues = (node, promFilter) => {
     return allBrancheshaveReturnValues(lastBodyNode, promFilter);
   }
 
-  case 'LabeledStatement':
   case 'WhileStatement':
   case 'DoWhileStatement':
+    if (node.test.value === true) {
+      // If this is an infinite loop, we assume only one branch
+      //   is needed to provide a return
+      return hasReturnValue(node.body, false, promFilter);
+    }
+
+    // Fallthrough
+  case 'LabeledStatement':
   case 'ForStatement':
   case 'ForInStatement':
   case 'ForOfStatement':

test/rules/assertions/requireReturnsCheck.js

@@ -654,6 +654,29 @@ export default {
         },
       ],
     },
+    {
+      code: `
+        /**
+         * @returns {number}
+         */
+        function foo() {
+          let n = 1;
+          while (n > 0.5) {
+            n = Math.random();
+            if (n < 0.2) {
+              return n;
+            }
+          }
+        }
+      `,
+      errors: [
+        {
+          line: 2,
+          message: 'JSDoc @returns declaration present but return expression not available in function.',
+        },
+      ],
+    },
+
   ],
   valid: [
     {
@@ -1576,5 +1599,20 @@ export default {
       };
   `,
     },
+    {
+      code: `
+        /**
+         * @returns {number}
+         */
+        function foo() {
+          while (true) {
+            const n = Math.random();
+            if (n < 0.5) {
+              return n;
+            }
+          }
+        }
+      `,
+    },
   ],
 };