restrict increment-decrement fixer while fixing the postfix unary exp…

src/rules/incrementDecrementRule.ts

@@ -80,7 +80,14 @@ function walk(context: Lint.WalkContext<Options>) {
 
     function complainOnNode(node: ts.PostfixUnaryExpression | ts.PrefixUnaryExpression) {
         const newOperatorText = node.operator === ts.SyntaxKind.PlusPlusToken ? "+= 1" : "-= 1";
-        const replacement = createReplacement(node, newOperatorText);
+        let replacement: Lint.Replacement | undefined;
+
+        if (
+            tsutils.isPrefixUnaryExpression(node) ||
+            node.parent.kind === ts.SyntaxKind.ExpressionStatement
+        ) {
+            replacement = createReplacement(node, newOperatorText);
+        }
 
         const failure = Rule.FAILURE_STRING_FACTORY(newOperatorText);
 

test/rules/increment-decrement/default/test.ts.fix

@@ -14,13 +14,16 @@ x - 1;
 1 - x;
 
 x + (x += 1);
-x + (x += 1);
+x + x++;
 
 x - (x -= 1);
-x - (x -= 1);
+x - x--;
 
 (x += 1) + x;
-(x += 1) + x;
+x++ + x;
 
 (x -= 1) - x;
-(x -= 1) - x;
+x-- - x;
+
+expect(x++)
+expect(x += 1)

test/rules/increment-decrement/default/test.ts.lint

@@ -38,3 +38,8 @@ x-- - x;
 ~~~       [minus]
 [plus]:       Use an explicit += 1 operator.
 [minus]:       Use an explicit -= 1 operator.
+
+expect(x++)
+       ~~~       [plus]
+expect(++x)
+       ~~~       [plus]