From c50d6da8b4ad5ad4eaee1b0b60f9ac062c057bc7 Mon Sep 17 00:00:00 2001
From: Charlie Marsh <charlie.r.marsh@gmail.com>
Date: Tue, 14 Mar 2023 14:27:21 -0400
Subject: [PATCH] Allow string percent formatting in os.getenv (#3518)

---
 .../test/fixtures/pylint/invalid_envvar_default.py    |  2 +-
 .../src/rules/pylint/rules/invalid_envvar_default.rs  | 11 +++++++++++
 .../src/rules/pylint/rules/invalid_envvar_value.rs    | 11 +++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/crates/ruff/resources/test/fixtures/pylint/invalid_envvar_default.py b/crates/ruff/resources/test/fixtures/pylint/invalid_envvar_default.py
index 739e029976..c07de79871 100644
--- a/crates/ruff/resources/test/fixtures/pylint/invalid_envvar_default.py
+++ b/crates/ruff/resources/test/fixtures/pylint/invalid_envvar_default.py
@@ -8,5 +8,5 @@ os.getenv("AA", "GOOD")
 os.getenv("AA", f"GOOD")
 os.getenv("AA", "GOOD" + "BAD")
 os.getenv("AA", "GOOD" + 1)
+os.getenv("AA", "GOOD %s" % "BAD")
 os.getenv("B", Z)
-
diff --git a/crates/ruff/src/rules/pylint/rules/invalid_envvar_default.rs b/crates/ruff/src/rules/pylint/rules/invalid_envvar_default.rs
index d10b87fcb6..22d4aa1379 100644
--- a/crates/ruff/src/rules/pylint/rules/invalid_envvar_default.rs
+++ b/crates/ruff/src/rules/pylint/rules/invalid_envvar_default.rs
@@ -49,6 +49,7 @@ fn is_valid_default(expr: &Expr) -> bool {
         return true;
     }
 
+    // Allow string concatenation.
     if let ExprKind::BinOp {
         left,
         right,
@@ -58,6 +59,16 @@ fn is_valid_default(expr: &Expr) -> bool {
         return is_valid_default(left) && is_valid_default(right);
     }
 
+    // Allow string formatting.
+    if let ExprKind::BinOp {
+        left,
+        op: Operator::Mod,
+        ..
+    } = &expr.node
+    {
+        return is_valid_default(left);
+    }
+
     // Otherwise, the default must be a string or `None`.
     matches!(
         expr.node,
diff --git a/crates/ruff/src/rules/pylint/rules/invalid_envvar_value.rs b/crates/ruff/src/rules/pylint/rules/invalid_envvar_value.rs
index 2b7ad2288a..6c8bc3b084 100644
--- a/crates/ruff/src/rules/pylint/rules/invalid_envvar_value.rs
+++ b/crates/ruff/src/rules/pylint/rules/invalid_envvar_value.rs
@@ -46,6 +46,7 @@ fn is_valid_key(expr: &Expr) -> bool {
         return true;
     }
 
+    // Allow string concatenation.
     if let ExprKind::BinOp {
         left,
         right,
@@ -55,6 +56,16 @@ fn is_valid_key(expr: &Expr) -> bool {
         return is_valid_key(left) && is_valid_key(right);
     }
 
+    // Allow string formatting.
+    if let ExprKind::BinOp {
+        left,
+        op: Operator::Mod,
+        ..
+    } = &expr.node
+    {
+        return is_valid_key(left);
+    }
+
     // Otherwise, the default must be a string.
     matches!(
         expr.node,