From 1d01aa316f5dd4c3241821821c3a6096bd480480 Mon Sep 17 00:00:00 2001
From: camc314 <18101008+camc314@users.noreply.github.com>
Date: Sat, 24 Aug 2024 22:58:38 +0000
Subject: [PATCH] feat(linter/unicorn): add partial fixer for
 `prefer-array-flat` (#5143)

---
 .../src/rules/unicorn/prefer_array_flat.rs    | 57 +++++++++++++++++--
 1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/crates/oxc_linter/src/rules/unicorn/prefer_array_flat.rs b/crates/oxc_linter/src/rules/unicorn/prefer_array_flat.rs
index 2c47dbf68b393..0b221321dd40d 100644
--- a/crates/oxc_linter/src/rules/unicorn/prefer_array_flat.rs
+++ b/crates/oxc_linter/src/rules/unicorn/prefer_array_flat.rs
@@ -58,7 +58,7 @@ declare_oxc_lint!(
     /// ```
     PreferArrayFlat,
     pedantic,
-    pending
+    conditional_fix
 );
 
 impl Rule for PreferArrayFlat {
@@ -100,7 +100,19 @@ fn check_array_flat_map_case<'a>(call_expr: &CallExpression<'a>, ctx: &LintConte
         return;
     }
 
-    ctx.diagnostic(prefer_array_flat_diagnostic(call_expr.span));
+    let target_fix_span = call_expr
+        .callee
+        .as_member_expression()
+        .and_then(oxc_ast::ast::MemberExpression::static_property_info)
+        .map(|v| Span::new(v.0.start, call_expr.span.end));
+
+    if let Some(span) = target_fix_span {
+        ctx.diagnostic_with_fix(prefer_array_flat_diagnostic(call_expr.span), |fixer| {
+            fixer.replace(span, "flat()")
+        });
+    } else {
+        ctx.diagnostic(prefer_array_flat_diagnostic(call_expr.span));
+    }
 }
 
 // `array.reduce((a, b) => a.concat(b), [])`
@@ -162,11 +174,26 @@ fn check_array_reduce_case<'a>(call_expr: &CallExpression<'a>, ctx: &LintContext
                     return;
                 }
 
-                ctx.diagnostic(prefer_array_flat_diagnostic(call_expr.span));
+                ctx.diagnostic_with_fix(prefer_array_flat_diagnostic(call_expr.span), |fixer| {
+                    let target_fix_span = call_expr
+                        .callee
+                        .as_member_expression()
+                        .and_then(oxc_ast::ast::MemberExpression::static_property_info)
+                        .map(|v| Span::new(v.0.start, call_expr.span.end));
+
+                    debug_assert!(target_fix_span.is_some());
+
+                    if let Some(span) = target_fix_span {
+                        fixer.replace(span, "flat()")
+                    } else {
+                        fixer.noop()
+                    }
+                });
             }
         }
     }
 
+    // `array.reduce((a, b) => [...a, ...b], [])`
     if let Expression::ArrayExpression(array_expr) = &expr_stmt.expression {
         if array_expr.elements.len() != 2 {
             return;
@@ -194,7 +221,21 @@ fn check_array_reduce_case<'a>(call_expr: &CallExpression<'a>, ctx: &LintContext
             return;
         }
 
-        ctx.diagnostic(prefer_array_flat_diagnostic(call_expr.span));
+        ctx.diagnostic_with_fix(prefer_array_flat_diagnostic(call_expr.span), |fixer| {
+            let target_fix_span = call_expr
+                .callee
+                .as_member_expression()
+                .and_then(oxc_ast::ast::MemberExpression::static_property_info)
+                .map(|v| Span::new(v.0.start, call_expr.span.end));
+
+            debug_assert!(target_fix_span.is_some());
+
+            if let Some(target_fix_span) = target_fix_span {
+                fixer.replace(target_fix_span, "flat()")
+            } else {
+                fixer.noop()
+            }
+        });
     };
 }
 
@@ -405,5 +446,11 @@ fn test() {
         r"[/**/].concat(some.array)",
     ];
 
-    Tester::new(PreferArrayFlat::NAME, pass, fail).test_and_snapshot();
+    let fix = vec![
+        ("array.flatMap(x => x)", "array.flat()"),
+        ("array.reduce((a, b) => a.concat(b), [])", "array.flat()"),
+        ("array.reduce((a, b) => [...a, ...b], [])", "array.flat()"),
+    ];
+
+    Tester::new(PreferArrayFlat::NAME, pass, fail).expect_fix(fix).test_and_snapshot();
 }