Merge pull request #63 from buildo/fix-assignments

Exclude assignement expressions from linting

Author: gabro

.github/release-drafter.yml

@@ -4,6 +4,9 @@ template: |
   $CHANGES
 
 categories:
+  - title: "🐞 Bug fixes"
+    labels:
+      - "bug"
   - title: "🔧 Dependency updates"
     labels:
       - "dependencies"

src/rules/no-discarded-pure-expression.ts

@@ -1,4 +1,7 @@
-import { ParserServices } from "@typescript-eslint/experimental-utils";
+import {
+  ParserServices,
+  AST_NODE_TYPES,
+} from "@typescript-eslint/experimental-utils";
 import { array, option, readonlyArray } from "fp-ts";
 import { constVoid, pipe } from "fp-ts/function";
 import { Option } from "fp-ts/Option";
@@ -78,41 +81,43 @@ export default createRule({
 
     return {
       ExpressionStatement(node) {
-        pipe(
-          node.expression,
-          typeOfNode,
-          option.filter((t) => {
-            if (t.isUnion()) {
-              return pipe(t.types, array.every(isPureDataType));
-            }
-            return isPureDataType(t);
-          }),
-          option.fold(constVoid, (t) => {
-            context.report({
-              node: node.expression,
-              messageId: "pureExpressionInStatementPosition",
-              data: {
-                dataType: t.isUnion()
-                  ? t.types[0]!.symbol.escapedName
-                  : t.symbol.escapedName,
-              },
-              suggest: [
-                {
-                  messageId: "addReturn",
-                  fix(fixer) {
-                    return fixer.insertTextBefore(node.expression, "return ");
-                  },
+        if (node.expression.type !== AST_NODE_TYPES.AssignmentExpression) {
+          pipe(
+            node.expression,
+            typeOfNode,
+            option.filter((t) => {
+              if (t.isUnion()) {
+                return pipe(t.types, array.every(isPureDataType));
+              }
+              return isPureDataType(t);
+            }),
+            option.fold(constVoid, (t) => {
+              context.report({
+                node: node.expression,
+                messageId: "pureExpressionInStatementPosition",
+                data: {
+                  dataType: t.isUnion()
+                    ? t.types[0]!.symbol.escapedName
+                    : t.symbol.escapedName,
                 },
-                {
-                  messageId: "runExpression",
-                  fix(fixer) {
-                    return fixer.insertTextAfter(node.expression, "()");
+                suggest: [
+                  {
+                    messageId: "addReturn",
+                    fix(fixer) {
+                      return fixer.insertTextBefore(node.expression, "return ");
+                    },
                   },
-                },
-              ],
-            });
-          })
-        );
+                  {
+                    messageId: "runExpression",
+                    fix(fixer) {
+                      return fixer.insertTextAfter(node.expression, "()");
+                    },
+                  },
+                ],
+              });
+            })
+          );
+        }
       },
       JSXAttribute(node) {
         const parameterWithVoidOrUknownReturnType = (

tests/rules/no-discarded-pure-expression.test.ts

@@ -72,6 +72,23 @@ ruleTester.run("no-discarded-pure-expression", rule, {
         foo(2, () => myCommand(), () => myCommand())
       `,
     },
+    {
+      // https://github.com/buildo/eslint-plugin-fp-ts/issues/62
+      code: stripIndent`
+        import { IO } from "fp-ts/IO";
+        import { IORef } from "fp-ts/IORef";
+
+        class Foo {
+          private readonly errors: IORef<string[]>;
+          readonly getErrors: IO<string[]>;
+
+          constructor() {
+            this.errors = new IORef([]);
+            this.getErrors = this.errors.read;
+          }
+        }
+      `,
+    },
   ],
   invalid: [
     {