fix: prefer conditional expressions rule

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+* fix: prefer conditional expressions rule breaks code with increment / decrement operators
+
 ## 4.7.0
 
 * feat: add static code diagnostics `avoid-throw-in-catch-block`, `avoid-unnecessary-type-assertions`, `avoid-unnecessary-type-casts`, `avoid-missing-enum-constant-in-map`

lib/src/analyzers/lint_analyzer/rules/rules_list/prefer_conditional_expressions/prefer_conditional_expressions_rule.dart

@@ -1,6 +1,7 @@
 // ignore_for_file: public_member_api_docs
 
 import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:meta/meta.dart';
 
@@ -72,7 +73,13 @@ class PreferConditionalExpressionsRule extends CommonRule {
       final firstExpression = thenStatement.rightHandSide;
       final secondExpression = elseStatement.rightHandSide;
 
-      return '$target = $condition ? $firstExpression : $secondExpression;';
+      final thenStatementOperator = thenStatement.operator.type;
+      final elseStatementOperator = elseStatement.operator.type;
+
+      return _isAssignmentOperatorNotEq(thenStatementOperator) &&
+              _isAssignmentOperatorNotEq(elseStatementOperator)
+          ? '$condition ? ${thenStatement.leftHandSide} ${thenStatementOperator.stringValue} $firstExpression : ${thenStatement.leftHandSide} ${elseStatementOperator.stringValue} $secondExpression;'
+          : '$target = $condition ? $firstExpression : $secondExpression;';
     }
 
     if (thenStatement is ReturnStatement && elseStatement is ReturnStatement) {
@@ -84,4 +91,7 @@ class PreferConditionalExpressionsRule extends CommonRule {
 
     return null;
   }
+
+  bool _isAssignmentOperatorNotEq(TokenType token) =>
+      token.isAssignmentOperator && token != TokenType.EQ;
 }

test/src/analyzers/lint_analyzer/rules/rules_list/prefer_conditional_expressions/examples/example.dart

@@ -140,3 +140,33 @@ int anotherTestFunction() {
     a = 6;
   }
 }
+
+int newCase() {
+  final cond = false;
+  final delta = 1;
+  final value = 9;
+  // LINT
+  if (cond) {
+    value += delta;
+  } else {
+    value -= delta;
+  }
+  // LINT
+  if (cond) {
+    value -= delta;
+  } else {
+    value += delta;
+  }
+  //LINT
+  if (cond) {
+    value -= 2;
+  } else {
+    value += 5;
+  }
+  //LINT
+  if (cond) {
+    value *= 2;
+  } else {
+    value /= 5;
+  }
+}

test/src/analyzers/lint_analyzer/rules/rules_list/prefer_conditional_expressions/prefer_conditional_expressions_rule_test.dart

@@ -26,10 +26,49 @@ void main() {
 
       RuleTestHelper.verifyIssues(
         issues: issues,
-        startOffsets: [111, 289, 426, 490, 557, 616, 889, 1040],
-        startLines: [11, 30, 45, 51, 58, 64, 93, 109],
-        startColumns: [3, 3, 3, 3, 3, 3, 3, 3],
-        endOffsets: [161, 345, 476, 543, 602, 663, 930, 1087],
+        startOffsets: [
+          111,
+          289,
+          426,
+          490,
+          557,
+          616,
+          889,
+          1040,
+          1496,
+          1575,
+          1653,
+          1723,
+        ],
+        startLines: [
+          11,
+          30,
+          45,
+          51,
+          58,
+          64,
+          93,
+          109,
+          149,
+          155,
+          161,
+          167,
+        ],
+        startColumns: [3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3],
+        endOffsets: [
+          161,
+          345,
+          476,
+          543,
+          602,
+          663,
+          930,
+          1087,
+          1562,
+          1641,
+          1711,
+          1781,
+        ],
         locationTexts: [
           'if (a == 3) {\n'
               '    a = 2;\n'
@@ -67,6 +106,26 @@ void main() {
               '    return 2;\n'
               '  else\n'
               '    return a;',
+          'if (cond) {\n'
+              '    value += delta;\n'
+              '  } else {\n'
+              '    value -= delta;\n'
+              '  }',
+          'if (cond) {\n'
+              '    value -= delta;\n'
+              '  } else {\n'
+              '    value += delta;\n'
+              '  }',
+          'if (cond) {\n'
+              '    value -= 2;\n'
+              '  } else {\n'
+              '    value += 5;\n'
+              '  }',
+          'if (cond) {\n'
+              '    value *= 2;\n'
+              '  } else {\n'
+              '    value /= 5;\n'
+              '  }',
         ],
         messages: [
           'Prefer conditional expression.',
@@ -77,6 +136,10 @@ void main() {
           'Prefer conditional expression.',
           'Prefer conditional expression.',
           'Prefer conditional expression.',
+          'Prefer conditional expression.',
+          'Prefer conditional expression.',
+          'Prefer conditional expression.',
+          'Prefer conditional expression.',
         ],
         replacements: [
           'a = a == 3 ? 2 : 3;',
@@ -87,6 +150,10 @@ void main() {
           'a = a == 12 ? 2 : 3;',
           'a = a == 17 ? 2 : 3;',
           'return a == 20 ? 2 : a;',
+          'cond ? value += delta : value -= delta;',
+          'cond ? value -= delta : value += delta;',
+          'cond ? value -= 2 : value += 5;',
+          'cond ? value *= 2 : value /= 5;',
         ],
         replacementComments: [
           'Convert to conditional expression.',
@@ -97,6 +164,10 @@ void main() {
           'Convert to conditional expression.',
           'Convert to conditional expression.',
           'Convert to conditional expression.',
+          'Convert to conditional expression.',
+          'Convert to conditional expression.',
+          'Convert to conditional expression.',
+          'Convert to conditional expression.',
         ],
       );
     });