Support switch statements in no-conditional-returns

FreePay · Oct 13, 2023 · e58481d · e58481d
1 parent 34c8179
commit e58481d
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diff --git a/packages/react-app/eslint-rules/no-conditional-returns.js b/packages/react-app/eslint-rules/no-conditional-returns.js
@@ -1,3 +1,6 @@
+
+// NB see noConditionalReturnsTestCases.ts
+
 // This no-conditional-returns eslint rule ensures that if any branch of an
 // if-statement or try/catch might return, then the whole statement always
 // returns or throws, and control flow never continues in the same
@@ -16,6 +19,10 @@ module.exports = {
         const ifHasReturn = hasAnyReturn(node.consequent);
         const elseHasReturn = node.alternate && hasAnyReturn(node.alternate);
         return ifHasReturn || elseHasReturn;
+      } else if (node.type === 'SwitchStatement') {
+        return node.cases.some((caseNode) => caseNode.consequent.some(hasAnyReturn));
+      } else if (node.type === 'SwitchCase') {
+        return node.consequent.some(hasAnyReturn);
       } else if (node.type === 'TryStatement') {
         const blockHasReturn = hasAnyReturn(node.block);
         const handlerHasReturn = node.handler && hasAnyReturn(node.handler.body);
@@ -34,6 +41,10 @@ module.exports = {
         const ifReturnsOrThrows = returnsOrThrowsUnconditionally(node.consequent);
         const elseReturnsOrThrows = node.alternate && returnsOrThrowsUnconditionally(node.alternate);
         return ifReturnsOrThrows && (elseReturnsOrThrows || node.alternate === null);
+      } else if (node.type === 'SwitchStatement') {
+        return node.cases.every((caseNode) => caseNode.consequent.some(returnsOrThrowsUnconditionally));
+      } else if (node.type === 'SwitchCase') {
+        return node.consequent.some(returnsOrThrowsUnconditionally);
       } else if (node.type === 'TryStatement') {
         const blockReturnsOrThrows = returnsOrThrowsUnconditionally(node.block);
         const handlerReturnsOrThrows = node.handler && returnsOrThrowsUnconditionally(node.handler.body);
@@ -66,6 +77,20 @@ module.exports = {
       }
     }
 
+    function checkSwitchStatement(switchStatement) {
+      if (switchStatement.cases.length < 1) return;
+
+      const anyCaseHasAnyReturn = switchStatement.cases.some(caseNode => hasAnyReturn(caseNode));
+      const allCasesReturnOrThrowUnconditionally = switchStatement.cases.every(caseNode => returnsOrThrowsUnconditionally(caseNode));
+
+      if (anyCaseHasAnyReturn && !allCasesReturnOrThrowUnconditionally) {
+        context.report({
+          node: switchStatement,
+          message: 'Expected all cases in the "switch" statement to unconditionally return or throw when any case has a return.',
+        });
+      }
+    }
+
     function checkTryCatch(tryStatement) {
       const blockHasAnyReturn = hasAnyReturn(tryStatement.block);
       const handlerExistsAndHasAnyReturn = tryStatement.handler && hasAnyReturn(tryStatement.handler.body);
@@ -88,6 +113,7 @@ module.exports = {
 
     return {
       IfStatement: checkConditional,
+      SwitchStatement: checkSwitchStatement,
       TryStatement: checkTryCatch,
     };
   },

diff --git a/packages/react-app/src/noConditionalReturnsTestCases.ts b/packages/react-app/src/noConditionalReturnsTestCases.ts
@@ -203,6 +203,22 @@
 //   }
 // }
 
+// export function testNonViolation26(s: 1 | 2 | 3): number {
+//   if (s === 1) return 5;
+//   else switch (s) {
+//     case 2: return 5;
+//     case 3: return 8;
+//   }
+// }
+
+// export function testNonViolation27(s: 1 | 2 | 3): number {
+//   switch (s) {
+//     case 1: if (s === 1) return 5; else return 9;
+//     case 2: return 5;
+//     case 3: return 8;
+//   }
+// }
+
 // // ********************************************************
 // // no-conditional-returns: examples of rule violations
 
@@ -389,3 +405,30 @@
 //   }
 //   return 13;
 // }
+
+// export function testViolation18(s: 1 | 2 | 3): number {
+//   if (s === 1) return 5;
+//   else switch (s) {
+//     case 2: return 5;
+//     case 3: console.log("hi");
+//   }
+//   return 8;
+// }
+
+// export function testViolation19(s: 1 | 2 | 3): number {
+//   switch (s) {
+//     case 1: if (s === 1) return 5; else return 9;
+//     case 2: console.log("hey"); break;
+//     case 3: return 8;
+//   }
+//   return 5;
+// }
+
+// export function testViolation20(s: 1 | 2 | 3): number {
+//   switch (s) {
+//     case 1: if (s === 1) return; else console.log('hi'); break;
+//     case 2: return 4;
+//     case 3: return 8;
+//   }
+//   return 8;
+// }