Fix WoltNavigationToolbar leading constraint (#361)

lib/src/widgets/wolt_navigation_toolbar.dart

@@ -110,11 +110,10 @@ class _ToolbarLayout extends MultiChildLayoutDelegate {
     if (hasChild(_ToolbarSlot.leading)) {
       final BoxConstraints constraints = BoxConstraints(
         maxWidth: size.width,
-        minHeight:
-            size.height, // The height should be exactly the height of the bar.
         maxHeight: size.height,
       );
-      leadingWidth = layoutChild(_ToolbarSlot.leading, constraints).width;
+      final Size leadingSize = layoutChild(_ToolbarSlot.leading, constraints);
+      leadingWidth = leadingSize.width;
       final double leadingX;
       switch (textDirection) {
         case TextDirection.rtl:
@@ -124,7 +123,8 @@ class _ToolbarLayout extends MultiChildLayoutDelegate {
           leadingX = 0.0;
           break;
       }
-      positionChild(_ToolbarSlot.leading, Offset(leadingX, 0.0));
+      final double leadingY = (size.height - leadingSize.height) / 2.0;
+      positionChild(_ToolbarSlot.leading, Offset(leadingX, leadingY));
     }
 
     if (hasChild(_ToolbarSlot.trailing)) {

test/widgets/wolt_navigation_toolbar_test.dart

@@ -0,0 +1,44 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:wolt_modal_sheet/src/widgets/wolt_navigation_toolbar.dart';
+
+void main() {
+  testWidgets(
+    'Leading/Trailing widget constaints',
+    (tester) async {
+      const IconData leadingIcon = Icons.chevron_left;
+      const IconData trailingIcon = Icons.chevron_right;
+      const double iconSize = 24.0;
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Material(
+            child: Center(
+              child: SizedBox(
+                height: 72.0,
+                child: WoltNavigationToolbar(
+                  leading: const ColoredBox(
+                    color: Color(0xFF00FF00),
+                    child: Icon(leadingIcon),
+                  ),
+                  trailing: Container(
+                    color: const Color(0xFFFF0000),
+                    child: const Icon(trailingIcon),
+                  ),
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+
+      final Size leadingSize = tester.getSize(find.ancestor(
+          of: find.byIcon(leadingIcon), matching: find.byType(ColoredBox)));
+      expect(leadingSize, const Size.square(iconSize));
+
+      final Size trailingSize = tester.getSize(find.ancestor(
+          of: find.byIcon(trailingIcon), matching: find.byType(ColoredBox)));
+      expect(trailingSize, const Size.square(iconSize));
+    },
+  );
+}