test: simplify tests in config.rs (#2586)

this is much easier to read, thanks @bolinfest for the suggestion.

codex-rs/core/src/config.rs

@@ -279,12 +279,14 @@ pub fn set_project_trusted(codex_home: &Path, project_path: &Path) -> anyhow::Re
     // Ensure top-level `projects` exists as a non-inline, explicit table. If it
     // exists but was previously represented as a non-table (e.g., inline),
     // replace it with an explicit table.
+    let mut created_projects_table = false;
     {
         let root = doc.as_table_mut();
         let needs_table = !root.contains_key("projects")
             || root.get("projects").and_then(|i| i.as_table()).is_none();
         if needs_table {
             root.insert("projects", toml_edit::table());
+            created_projects_table = true;
         }
     }
     let Some(projects_tbl) = doc["projects"].as_table_mut() else {
@@ -293,6 +295,12 @@ pub fn set_project_trusted(codex_home: &Path, project_path: &Path) -> anyhow::Re
         ));
     };
 
+    // If we created the `projects` table ourselves, keep it implicit so we
+    // don't render a standalone `[projects]` header.
+    if created_projects_table {
+        projects_tbl.set_implicit(true);
+    }
+
     // Ensure the per-project entry is its own explicit table. If it exists but
     // is not a table (e.g., an inline table), replace it with an explicit table.
     let needs_proj_table = !projects_tbl.contains_key(project_key.as_str())
@@ -1254,37 +1262,22 @@ disable_response_storage = true
         // Call the function under test
         set_project_trusted(codex_home.path(), project_dir.path())?;
 
-        // Read back the generated config.toml
+        // Read back the generated config.toml and assert exact contents
         let config_path = codex_home.path().join(CONFIG_TOML_FILE);
         let contents = std::fs::read_to_string(&config_path)?;
 
-        // Verify it does not use inline tables for the project entry
-        assert!(
-            !contents.contains("{ trust_level"),
-            "config.toml should not use inline tables:\n{}",
-            contents
-        );
-
-        // Verify the explicit table for the project exists. toml_edit may choose
-        // either basic (double-quoted) or literal (single-quoted) strings for keys
-        // containing backslashes (e.g., on Windows). Accept both forms.
-        let path_str = project_dir.path().to_string_lossy();
-        let project_key_double = format!("[projects.\"{}\"]", path_str);
-        let project_key_single = format!("[projects.'{}']", path_str);
-        assert!(
-            contents.contains(&project_key_double) || contents.contains(&project_key_single),
-            "missing explicit project table header: expected to find `{}` or `{}` in:\n{}",
-            project_key_double,
-            project_key_single,
-            contents
-        );
-
-        // Verify the trust_level entry
-        assert!(
-            contents.contains("trust_level = \"trusted\""),
-            "missing trust_level entry in:\n{}",
-            contents
+        let raw_path = project_dir.path().to_string_lossy();
+        let path_str = if raw_path.contains('\\') {
+            format!("'{}'", raw_path)
+        } else {
+            format!("\"{}\"", raw_path)
+        };
+        let expected = format!(
+            r#"[projects.{path_str}]
+trust_level = "trusted"
+"#
         );
+        assert_eq!(contents, expected);
 
         Ok(())
     }
@@ -1296,11 +1289,17 @@ disable_response_storage = true
 
         // Seed config.toml with an inline project entry under [projects]
         let config_path = codex_home.path().join(CONFIG_TOML_FILE);
-        let path_str = project_dir.path().to_string_lossy();
-        // Use a literal-quoted key so Windows backslashes don't require escaping
+        let raw_path = project_dir.path().to_string_lossy();
+        let path_str = if raw_path.contains('\\') {
+            format!("'{}'", raw_path)
+        } else {
+            format!("\"{}\"", raw_path)
+        };
+        // Use a quoted key so backslashes don't require escaping on Windows
         let initial = format!(
-            "[projects]\n'{}' = {{ trust_level = \"untrusted\" }}\n",
-            path_str
+            r#"[projects]
+{path_str} = {{ trust_level = "untrusted" }}
+"#
         );
         std::fs::create_dir_all(codex_home.path())?;
         std::fs::write(&config_path, initial)?;
@@ -1310,28 +1309,15 @@ disable_response_storage = true
 
         let contents = std::fs::read_to_string(&config_path)?;
 
-        // Should not contain inline table representation anymore (accept both quote styles)
-        let inline_double = format!("\"{}\" = {{ trust_level = \"trusted\" }}", path_str);
-        let inline_single = format!("'{}' = {{ trust_level = \"trusted\" }}", path_str);
-        assert!(
-            !contents.contains(&inline_double) && !contents.contains(&inline_single),
-            "config.toml should not contain inline project table anymore:\n{}",
-            contents
-        );
+        // Assert exact output after conversion to explicit table
+        let expected = format!(
+            r#"[projects]
 
-        // And explicit child table header for the project
-        let project_key_double = format!("[projects.\"{}\"]", path_str);
-        let project_key_single = format!("[projects.'{}']", path_str);
-        assert!(
-            contents.contains(&project_key_double) || contents.contains(&project_key_single),
-            "missing explicit project table header: expected to find `{}` or `{}` in:\n{}",
-            project_key_double,
-            project_key_single,
-            contents
+[projects.{path_str}]
+trust_level = "trusted"
+"#
         );
-
-        // And the trust level value
-        assert!(contents.contains("trust_level = \"trusted\""));
+        assert_eq!(contents, expected);
 
         Ok(())
     }