Added identical(a,b) short circuit to Material Library lerp methods (#120829)

packages/flutter/lib/src/material/app_bar_theme.dart

@@ -204,6 +204,9 @@ class AppBarTheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static AppBarTheme lerp(AppBarTheme? a, AppBarTheme? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return AppBarTheme(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
       foregroundColor: Color.lerp(a?.foregroundColor, b?.foregroundColor, t),

packages/flutter/lib/src/material/badge_theme.dart

@@ -94,6 +94,9 @@ class BadgeThemeData with Diagnosticable {
 
   /// Linearly interpolate between two [Badge] themes.
   static BadgeThemeData lerp(BadgeThemeData? a, BadgeThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return BadgeThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
       textColor: Color.lerp(a?.textColor, b?.textColor, t),

packages/flutter/lib/src/material/bottom_app_bar_theme.dart

@@ -94,6 +94,9 @@ class BottomAppBarTheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BottomAppBarTheme lerp(BottomAppBarTheme? a, BottomAppBarTheme? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return BottomAppBarTheme(
       color: Color.lerp(a?.color, b?.color, t),
       elevation: lerpDouble(a?.elevation, b?.elevation, t),

packages/flutter/lib/src/material/bottom_navigation_bar_theme.dart

@@ -174,6 +174,9 @@ class BottomNavigationBarThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BottomNavigationBarThemeData lerp(BottomNavigationBarThemeData? a, BottomNavigationBarThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return BottomNavigationBarThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
       elevation: lerpDouble(a?.elevation, b?.elevation, t),

packages/flutter/lib/src/material/bottom_sheet_theme.dart

@@ -118,8 +118,8 @@ class BottomSheetThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static BottomSheetThemeData? lerp(BottomSheetThemeData? a, BottomSheetThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return BottomSheetThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),

packages/flutter/lib/src/material/button_bar_theme.dart

@@ -146,8 +146,8 @@ class ButtonBarThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static ButtonBarThemeData? lerp(ButtonBarThemeData? a, ButtonBarThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ButtonBarThemeData(
       alignment: t < 0.5 ? a?.alignment : b?.alignment,

packages/flutter/lib/src/material/button_style.dart

@@ -492,8 +492,8 @@ class ButtonStyle with Diagnosticable {
 
   /// Linearly interpolate between two [ButtonStyle]s.
   static ButtonStyle? lerp(ButtonStyle? a, ButtonStyle? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ButtonStyle(
       textStyle: MaterialStateProperty.lerp<TextStyle?>(a?.textStyle, b?.textStyle, t, TextStyle.lerp),

packages/flutter/lib/src/material/card_theme.dart

@@ -114,6 +114,9 @@ class CardTheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static CardTheme lerp(CardTheme? a, CardTheme? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return CardTheme(
       clipBehavior: t < 0.5 ? a?.clipBehavior : b?.clipBehavior,
       color: Color.lerp(a?.color, b?.color, t),

packages/flutter/lib/src/material/checkbox_theme.dart

@@ -130,6 +130,9 @@ class CheckboxThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static CheckboxThemeData lerp(CheckboxThemeData? a, CheckboxThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return CheckboxThemeData(
       mouseCursor: t < 0.5 ? a?.mouseCursor : b?.mouseCursor,
       fillColor: MaterialStateProperty.lerp<Color?>(a?.fillColor, b?.fillColor, t, Color.lerp),
@@ -195,6 +198,9 @@ class CheckboxThemeData with Diagnosticable {
     if (a == null || b == null) {
       return null;
     }
+    if (identical(a, b)) {
+      return a;
+    }
     return BorderSide.lerp(a, b, t);
   }
 }

packages/flutter/lib/src/material/chip_theme.dart

@@ -483,8 +483,8 @@ class ChipThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static ChipThemeData? lerp(ChipThemeData? a, ChipThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ChipThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),

packages/flutter/lib/src/material/color_scheme.dart

@@ -827,6 +827,9 @@ class ColorScheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static ColorScheme lerp(ColorScheme a, ColorScheme b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return ColorScheme(
       brightness: t < 0.5 ? a.brightness : b.brightness,
       primary: Color.lerp(a.primary, b.primary, t)!,

packages/flutter/lib/src/material/data_table_theme.dart

@@ -122,6 +122,9 @@ class DataTableThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static DataTableThemeData lerp(DataTableThemeData a, DataTableThemeData b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return DataTableThemeData(
       decoration: Decoration.lerp(a.decoration, b.decoration, t),
       dataRowColor: MaterialStateProperty.lerp<Color?>(a.dataRowColor, b.dataRowColor, t, Color.lerp),

packages/flutter/lib/src/material/date_picker_theme.dart

@@ -356,6 +356,9 @@ class DatePickerThemeData with Diagnosticable {
 
   /// Linearly interpolates between two [DatePickerThemeData].
   static DatePickerThemeData lerp(DatePickerThemeData? a, DatePickerThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return DatePickerThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
       elevation: lerpDouble(a?.elevation, b?.elevation, t),
@@ -393,8 +396,8 @@ class DatePickerThemeData with Diagnosticable {
   }
 
   static BorderSide? _lerpBorderSide(BorderSide? a, BorderSide? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     if (a == null) {
       return BorderSide.lerp(BorderSide(width: 0, color: b!.color.withAlpha(0)), b, t);

packages/flutter/lib/src/material/dialog_theme.dart

@@ -111,6 +111,9 @@ class DialogTheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static DialogTheme lerp(DialogTheme? a, DialogTheme? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return DialogTheme(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
       elevation: lerpDouble(a?.elevation, b?.elevation, t),

packages/flutter/lib/src/material/divider_theme.dart

@@ -87,6 +87,9 @@ class DividerThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static DividerThemeData lerp(DividerThemeData? a, DividerThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return DividerThemeData(
       color: Color.lerp(a?.color, b?.color, t),
       space: lerpDouble(a?.space, b?.space, t),

packages/flutter/lib/src/material/drawer_theme.dart

@@ -99,8 +99,8 @@ class DrawerThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static DrawerThemeData? lerp(DrawerThemeData? a, DrawerThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return DrawerThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),

packages/flutter/lib/src/material/dropdown_menu_theme.dart

@@ -64,6 +64,9 @@ class DropdownMenuThemeData with Diagnosticable {
 
   /// Linearly interpolates between two dropdown menu themes.
   static DropdownMenuThemeData lerp(DropdownMenuThemeData? a, DropdownMenuThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return DropdownMenuThemeData(
       textStyle: TextStyle.lerp(a?.textStyle, b?.textStyle, t),
       inputDecorationTheme: t < 0.5 ? a?.inputDecorationTheme : b?.inputDecorationTheme,

packages/flutter/lib/src/material/elevated_button_theme.dart

@@ -49,8 +49,8 @@ class ElevatedButtonThemeData with Diagnosticable {
 
   /// Linearly interpolate between two elevated button themes.
   static ElevatedButtonThemeData? lerp(ElevatedButtonThemeData? a, ElevatedButtonThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ElevatedButtonThemeData(
       style: ButtonStyle.lerp(a?.style, b?.style, t),

packages/flutter/lib/src/material/expansion_tile_theme.dart

@@ -124,8 +124,8 @@ class ExpansionTileThemeData with Diagnosticable {
 
   /// Linearly interpolate between ExpansionTileThemeData objects.
   static ExpansionTileThemeData? lerp(ExpansionTileThemeData? a, ExpansionTileThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ExpansionTileThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),

packages/flutter/lib/src/material/filled_button_theme.dart

@@ -49,8 +49,8 @@ class FilledButtonThemeData with Diagnosticable {
 
   /// Linearly interpolate between two filled button themes.
   static FilledButtonThemeData? lerp(FilledButtonThemeData? a, FilledButtonThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return FilledButtonThemeData(
       style: ButtonStyle.lerp(a?.style, b?.style, t),

packages/flutter/lib/src/material/floating_action_button_theme.dart

@@ -193,8 +193,8 @@ class FloatingActionButtonThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static FloatingActionButtonThemeData? lerp(FloatingActionButtonThemeData? a, FloatingActionButtonThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return FloatingActionButtonThemeData(
       foregroundColor: Color.lerp(a?.foregroundColor, b?.foregroundColor, t),

packages/flutter/lib/src/material/icon_button_theme.dart

@@ -49,8 +49,8 @@ class IconButtonThemeData with Diagnosticable {
 
   /// Linearly interpolate between two icon button themes.
   static IconButtonThemeData? lerp(IconButtonThemeData? a, IconButtonThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return IconButtonThemeData(
       style: ButtonStyle.lerp(a?.style, b?.style, t),

packages/flutter/lib/src/material/list_tile_theme.dart

@@ -172,8 +172,8 @@ class ListTileThemeData with Diagnosticable {
 
   /// Linearly interpolate between ListTileThemeData objects.
   static ListTileThemeData? lerp(ListTileThemeData? a, ListTileThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ListTileThemeData(
       dense: t < 0.5 ? a?.dense : b?.dense,

packages/flutter/lib/src/material/menu_bar_theme.dart

@@ -41,8 +41,11 @@ class MenuBarThemeData extends MenuThemeData {
   /// Creates a const set of properties used to configure [MenuTheme].
   const MenuBarThemeData({super.style});
 
-  /// Linearly interpolate between two text button themes.
+  /// Linearly interpolate between two [MenuBar] themes.
   static MenuBarThemeData? lerp(MenuBarThemeData? a, MenuBarThemeData? b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return MenuBarThemeData(style: MenuStyle.lerp(a?.style, b?.style, t));
   }
 }

packages/flutter/lib/src/material/menu_button_theme.dart

@@ -59,6 +59,9 @@ class MenuButtonThemeData with Diagnosticable {
 
   /// Linearly interpolate between two menu button themes.
   static MenuButtonThemeData? lerp(MenuButtonThemeData? a, MenuButtonThemeData? b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return MenuButtonThemeData(style: ButtonStyle.lerp(a?.style, b?.style, t));
   }
 

packages/flutter/lib/src/material/menu_style.dart

@@ -304,8 +304,8 @@ class MenuStyle with Diagnosticable {
 
   /// Linearly interpolate between two [MenuStyle]s.
   static MenuStyle? lerp(MenuStyle? a, MenuStyle? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return MenuStyle(
       backgroundColor: MaterialStateProperty.lerp<Color?>(a?.backgroundColor, b?.backgroundColor, t, Color.lerp),

packages/flutter/lib/src/material/menu_theme.dart

@@ -43,6 +43,9 @@ class MenuThemeData with Diagnosticable {
 
   /// Linearly interpolate between two menu button themes.
   static MenuThemeData? lerp(MenuThemeData? a, MenuThemeData? b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return MenuThemeData(style: MenuStyle.lerp(a?.style, b?.style, t));
   }
 

packages/flutter/lib/src/material/navigation_bar_theme.dart

@@ -125,8 +125,8 @@ class NavigationBarThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static NavigationBarThemeData? lerp(NavigationBarThemeData? a, NavigationBarThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return NavigationBarThemeData(
       height: lerpDouble(a?.height, b?.height, t),

packages/flutter/lib/src/material/navigation_drawer_theme.dart

@@ -124,10 +124,9 @@ class NavigationDrawerThemeData with Diagnosticable {
   /// If both arguments are null then null is returned.
   ///
   /// {@macro dart.ui.shadow.lerp}
-  static NavigationDrawerThemeData? lerp(
-      NavigationDrawerThemeData? a, NavigationDrawerThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+  static NavigationDrawerThemeData? lerp(NavigationDrawerThemeData? a, NavigationDrawerThemeData? b, double t) {
+    if (identical(a, b)) {
+      return a;
     }
     return NavigationDrawerThemeData(
       tileHeight: lerpDouble(a?.tileHeight, b?.tileHeight, t),

packages/flutter/lib/src/material/navigation_rail_theme.dart

@@ -143,8 +143,8 @@ class NavigationRailThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static NavigationRailThemeData? lerp(NavigationRailThemeData? a, NavigationRailThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return NavigationRailThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),

packages/flutter/lib/src/material/outlined_button_theme.dart

@@ -49,8 +49,8 @@ class OutlinedButtonThemeData with Diagnosticable {
 
   /// Linearly interpolate between two outlined button themes.
   static OutlinedButtonThemeData? lerp(OutlinedButtonThemeData? a, OutlinedButtonThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return OutlinedButtonThemeData(
       style: ButtonStyle.lerp(a?.style, b?.style, t),

packages/flutter/lib/src/material/popup_menu_theme.dart

@@ -129,8 +129,8 @@ class PopupMenuThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static PopupMenuThemeData? lerp(PopupMenuThemeData? a, PopupMenuThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return PopupMenuThemeData(
       color: Color.lerp(a?.color, b?.color, t),

packages/flutter/lib/src/material/progress_indicator_theme.dart

@@ -84,8 +84,8 @@ class ProgressIndicatorThemeData with Diagnosticable {
   ///
   /// If both arguments are null, then null is returned.
   static ProgressIndicatorThemeData? lerp(ProgressIndicatorThemeData? a, ProgressIndicatorThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ProgressIndicatorThemeData(
       color: Color.lerp(a?.color, b?.color, t),

packages/flutter/lib/src/material/radio_theme.dart

@@ -112,6 +112,9 @@ class RadioThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static RadioThemeData lerp(RadioThemeData? a, RadioThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return RadioThemeData(
       mouseCursor: t < 0.5 ? a?.mouseCursor : b?.mouseCursor,
       fillColor: MaterialStateProperty.lerp<Color?>(a?.fillColor, b?.fillColor, t, Color.lerp),

packages/flutter/lib/src/material/scrollbar_theme.dart

@@ -204,6 +204,9 @@ class ScrollbarThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static ScrollbarThemeData lerp(ScrollbarThemeData? a, ScrollbarThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return ScrollbarThemeData(
       thumbVisibility: MaterialStateProperty.lerp<bool?>(a?.thumbVisibility, b?.thumbVisibility, t, _lerpBool),
       thickness: MaterialStateProperty.lerp<double?>(a?.thickness, b?.thickness, t, lerpDouble),

packages/flutter/lib/src/material/segmented_button_theme.dart

@@ -62,6 +62,9 @@ class SegmentedButtonThemeData with Diagnosticable {
 
   /// Linearly interpolates between two segmented button themes.
   static SegmentedButtonThemeData lerp(SegmentedButtonThemeData? a, SegmentedButtonThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return SegmentedButtonThemeData(
       style: ButtonStyle.lerp(a?.style, b?.style, t),
       selectedIcon: t < 0.5 ? a?.selectedIcon : b?.selectedIcon,

packages/flutter/lib/src/material/slider_theme.dart

@@ -650,6 +650,9 @@ class SliderThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static SliderThemeData lerp(SliderThemeData a, SliderThemeData b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return SliderThemeData(
       trackHeight: lerpDouble(a.trackHeight, b.trackHeight, t),
       activeTrackColor: Color.lerp(a.activeTrackColor, b.activeTrackColor, t),

packages/flutter/lib/src/material/snack_bar_theme.dart

@@ -178,6 +178,9 @@ class SnackBarThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static SnackBarThemeData lerp(SnackBarThemeData? a, SnackBarThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return SnackBarThemeData(
       backgroundColor: Color.lerp(a?.backgroundColor, b?.backgroundColor, t),
       actionTextColor: Color.lerp(a?.actionTextColor, b?.actionTextColor, t),

packages/flutter/lib/src/material/switch_theme.dart

@@ -116,6 +116,9 @@ class SwitchThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static SwitchThemeData lerp(SwitchThemeData? a, SwitchThemeData? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return SwitchThemeData(
       thumbColor: MaterialStateProperty.lerp<Color?>(a?.thumbColor, b?.thumbColor, t, Color.lerp),
       trackColor: MaterialStateProperty.lerp<Color?>(a?.trackColor, b?.trackColor, t, Color.lerp),

packages/flutter/lib/src/material/tab_bar_theme.dart

@@ -133,6 +133,9 @@ class TabBarTheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static TabBarTheme lerp(TabBarTheme a, TabBarTheme b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return TabBarTheme(
       indicator: Decoration.lerp(a.indicator, b.indicator, t),
       indicatorColor: Color.lerp(a.indicatorColor, b.indicatorColor, t),

packages/flutter/lib/src/material/text_button_theme.dart

@@ -49,8 +49,8 @@ class TextButtonThemeData with Diagnosticable {
 
   /// Linearly interpolate between two text button themes.
   static TextButtonThemeData? lerp(TextButtonThemeData? a, TextButtonThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return TextButtonThemeData(
       style: ButtonStyle.lerp(a?.style, b?.style, t),

packages/flutter/lib/src/material/text_selection_theme.dart

@@ -73,8 +73,8 @@ class TextSelectionThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static TextSelectionThemeData? lerp(TextSelectionThemeData? a, TextSelectionThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return TextSelectionThemeData(
       cursorColor: Color.lerp(a?.cursorColor, b?.cursorColor, t),

packages/flutter/lib/src/material/text_theme.dart

@@ -799,6 +799,9 @@ class TextTheme with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static TextTheme lerp(TextTheme? a, TextTheme? b, double t) {
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     return TextTheme(
       displayLarge: TextStyle.lerp(a?.displayLarge, b?.displayLarge, t),
       displayMedium: TextStyle.lerp(a?.displayMedium, b?.displayMedium, t),

packages/flutter/lib/src/material/theme_data.dart

@@ -1978,6 +1978,9 @@ class ThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static ThemeData lerp(ThemeData a, ThemeData b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return ThemeData.raw(
       // For the sanity of the reader, make sure these properties are in the same
       // order in every place that they are separated by section comments (e.g.
@@ -2732,6 +2735,9 @@ class VisualDensity with Diagnosticable {
 
   /// Linearly interpolate between two densities.
   static VisualDensity lerp(VisualDensity a, VisualDensity b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return VisualDensity(
       horizontal: lerpDouble(a.horizontal, b.horizontal, t)!,
       vertical: lerpDouble(a.vertical, b.vertical, t)!,

packages/flutter/lib/src/material/time_picker_theme.dart

@@ -299,7 +299,9 @@ class TimePickerThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static TimePickerThemeData lerp(TimePickerThemeData? a, TimePickerThemeData? b, double t) {
-
+    if (identical(a, b) && a != null) {
+      return a;
+    }
     // Workaround since BorderSide's lerp does not allow for null arguments.
     BorderSide? lerpedBorderSide;
     if (a?.dayPeriodBorderSide == null && b?.dayPeriodBorderSide == null) {

packages/flutter/lib/src/material/toggle_buttons_theme.dart

@@ -150,8 +150,8 @@ class ToggleButtonsThemeData with Diagnosticable {
 
   /// Linearly interpolate between two toggle buttons themes.
   static ToggleButtonsThemeData? lerp(ToggleButtonsThemeData? a, ToggleButtonsThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return ToggleButtonsThemeData(
       textStyle: TextStyle.lerp(a?.textStyle, b?.textStyle, t),

packages/flutter/lib/src/material/tooltip_theme.dart

@@ -149,8 +149,8 @@ class TooltipThemeData with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static TooltipThemeData? lerp(TooltipThemeData? a, TooltipThemeData? b, double t) {
-    if (a == null && b == null) {
-      return null;
+    if (identical(a, b)) {
+      return a;
     }
     return TooltipThemeData(
       height: lerpDouble(a?.height, b?.height, t),

packages/flutter/lib/src/material/typography.dart

@@ -329,6 +329,9 @@ class Typography with Diagnosticable {
   ///
   /// {@macro dart.ui.shadow.lerp}
   static Typography lerp(Typography a, Typography b, double t) {
+    if (identical(a, b)) {
+      return a;
+    }
     return Typography._(
       TextTheme.lerp(a.black, b.black, t),
       TextTheme.lerp(a.white, b.white, t),

packages/flutter/test/material/app_bar_theme_test.dart

@@ -14,6 +14,11 @@ void main() {
     expect(const AppBarTheme().hashCode, const AppBarTheme().copyWith().hashCode);
   });
 
+  test('AppBarTheme lerp special cases', () {
+    const AppBarTheme data = AppBarTheme();
+    expect(identical(AppBarTheme.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no AppBarTheme returns defaults', (WidgetTester tester) async {
     final ThemeData theme = ThemeData();
     await tester.pumpWidget(

packages/flutter/test/material/badge_theme_test.dart

@@ -14,6 +14,12 @@ void main() {
     expect(const BadgeThemeData().hashCode, const BadgeThemeData().copyWith().hashCode);
   });
 
+  test('BadgeThemeData lerp special cases', () {
+    expect(BadgeThemeData.lerp(null, null, 0), const BadgeThemeData());
+    const BadgeThemeData data = BadgeThemeData();
+    expect(identical(BadgeThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('BadgeThemeData defaults', () {
     const BadgeThemeData themeData = BadgeThemeData();
     expect(themeData.backgroundColor, null);

packages/flutter/test/material/bottom_app_bar_theme_test.dart

@@ -11,6 +11,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('BottomAppBarTheme lerp special cases', () {
+    expect(BottomAppBarTheme.lerp(null, null, 0), const BottomAppBarTheme());
+    const BottomAppBarTheme data = BottomAppBarTheme();
+    expect(identical(BottomAppBarTheme.lerp(data, data, 0.5), data), true);
+  });
+
   group('Material 2 tests', () {
     testWidgets('BAB theme overrides color', (WidgetTester tester) async {
       const Color themedColor = Colors.black87;

packages/flutter/test/material/bottom_navigation_bar_theme_test.dart

@@ -15,6 +15,11 @@ void main() {
     expect(const BottomNavigationBarThemeData().hashCode, const BottomNavigationBarThemeData().copyWith().hashCode);
   });
 
+  test('BottomNavigationBarThemeData lerp special cases', () {
+    const BottomNavigationBarThemeData data = BottomNavigationBarThemeData();
+    expect(identical(BottomNavigationBarThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('BottomNavigationBarThemeData defaults', () {
     const BottomNavigationBarThemeData themeData = BottomNavigationBarThemeData();
     expect(themeData.backgroundColor, null);

packages/flutter/test/material/bottom_sheet_theme_test.dart

@@ -12,6 +12,18 @@ void main() {
     expect(const BottomSheetThemeData().hashCode, const BottomSheetThemeData().copyWith().hashCode);
   });
 
+  test('BottomSheetThemeData lerp special cases', () {
+    expect(BottomSheetThemeData.lerp(null, null, 0), null);
+    const BottomSheetThemeData data = BottomSheetThemeData();
+    expect(identical(BottomSheetThemeData.lerp(data, data, 0.5), data), true);
+  });
+
+  test('BottomSheetThemeData lerp special cases', () {
+    expect(BottomSheetThemeData.lerp(null, null, 0), null);
+    const BottomSheetThemeData data = BottomSheetThemeData();
+    expect(identical(BottomSheetThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('BottomSheetThemeData null fields by default', () {
     const BottomSheetThemeData bottomSheetTheme = BottomSheetThemeData();
     expect(bottomSheetTheme.backgroundColor, null);

packages/flutter/test/material/button_bar_theme_test.dart

@@ -8,6 +8,12 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() {
 
+  test('ButtonBarThemeData lerp special cases', () {
+    expect(ButtonBarThemeData.lerp(null, null, 0), null);
+    const ButtonBarThemeData data = ButtonBarThemeData();
+    expect(identical(ButtonBarThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('ButtonBarThemeData null fields by default', () {
     const ButtonBarThemeData buttonBarTheme = ButtonBarThemeData();
     expect(buttonBarTheme.alignment, null);

packages/flutter/test/material/button_style_test.dart

@@ -14,6 +14,12 @@ void main() {
     expect(const ButtonStyle().hashCode, const ButtonStyle().copyWith().hashCode);
   });
 
+  test('ButtonStyle lerp special cases', () {
+    expect(ButtonStyle.lerp(null, null, 0), null);
+    const ButtonStyle data = ButtonStyle();
+    expect(identical(ButtonStyle.lerp(data, data, 0.5), data), true);
+  });
+
   test('ButtonStyle defaults', () {
     const ButtonStyle style = ButtonStyle();
     expect(style.textStyle, null);

packages/flutter/test/material/card_theme_test.dart

@@ -16,6 +16,12 @@ void main() {
     expect(const CardTheme().hashCode, const CardTheme().copyWith().hashCode);
   });
 
+  test('CardTheme lerp special cases', () {
+    expect(CardTheme.lerp(null, null, 0), const CardTheme());
+    const CardTheme theme = CardTheme();
+    expect(identical(CardTheme.lerp(theme, theme, 0.5), theme), true);
+  });
+
   testWidgets('Passing no CardTheme returns defaults', (WidgetTester tester) async {
     final ThemeData theme = ThemeData(useMaterial3: true);
     await tester.pumpWidget(MaterialApp(

packages/flutter/test/material/checkbox_theme_test.dart

@@ -15,6 +15,12 @@ void main() {
     expect(const CheckboxThemeData().hashCode, const CheckboxThemeData().copyWith().hashCode);
   });
 
+  test('CheckboxThemeData lerp special cases', () {
+    expect(CheckboxThemeData.lerp(null, null, 0), const CheckboxThemeData());
+    const CheckboxThemeData data = CheckboxThemeData();
+    expect(identical(CheckboxThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('CheckboxThemeData defaults', () {
     const CheckboxThemeData themeData = CheckboxThemeData();
     expect(themeData.mouseCursor, null);

packages/flutter/test/material/chip_theme_test.dart

@@ -42,6 +42,12 @@ void main() {
     expect(const ChipThemeData().hashCode, const ChipThemeData().copyWith().hashCode);
   });
 
+  test('ChipThemeData lerp special cases', () {
+    expect(ChipThemeData.lerp(null, null, 0), null);
+    const ChipThemeData data = ChipThemeData();
+    expect(identical(ChipThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('ChipThemeData defaults', () {
     const ChipThemeData themeData = ChipThemeData();
     expect(themeData.backgroundColor, null);

packages/flutter/test/material/color_scheme_test.dart

@@ -6,6 +6,11 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('ColorScheme lerp special cases', () {
+    const ColorScheme scheme = ColorScheme.light();
+    expect(identical(ColorScheme.lerp(scheme, scheme, 0.5), scheme), true);
+  });
+
   test('light scheme matches the spec', () {
     // Colors should match the Material Design baseline default theme:
     // https://material.io/design/color/dark-theme.html#ui-application

packages/flutter/test/material/data_table_theme_test.dart

@@ -12,6 +12,11 @@ void main() {
     expect(const DataTableThemeData().hashCode, const DataTableThemeData().copyWith().hashCode);
   });
 
+  test('DataTableThemeData lerp special cases', () {
+    const DataTableThemeData data = DataTableThemeData();
+    expect(identical(DataTableThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('DataTableThemeData defaults', () {
     const DataTableThemeData themeData = DataTableThemeData();
     expect(themeData.decoration, null);

packages/flutter/test/material/date_picker_theme_test.dart

@@ -75,6 +75,11 @@ void main() {
     expect(const DatePickerThemeData().hashCode, const DatePickerThemeData().copyWith().hashCode);
   });
 
+  test('DatePickerThemeData lerp special cases', () {
+    const DatePickerThemeData data = DatePickerThemeData();
+    expect(identical(DatePickerThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('DatePickerThemeData defaults', () {
     const DatePickerThemeData theme = DatePickerThemeData();
     expect(theme.backgroundColor, null);

packages/flutter/test/material/dialog_theme_test.dart

@@ -47,6 +47,12 @@ RenderParagraph _getTextRenderObject(WidgetTester tester, String text) {
 }
 
 void main() {
+  test('DialogTheme lerp special cases', () {
+    expect(DialogTheme.lerp(null, null, 0), const DialogTheme());
+    const DialogTheme theme = DialogTheme();
+    expect(identical(DialogTheme.lerp(theme, theme, 0.5), theme), true);
+  });
+
   testWidgets('Dialog Theme implements debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const DialogTheme(

packages/flutter/test/material/drawer_theme_test.dart

@@ -12,6 +12,12 @@ void main() {
     expect(const DrawerThemeData().hashCode, const DrawerThemeData().copyWith().hashCode);
   });
 
+  test('DrawerThemeData lerp special cases', () {
+    expect(DrawerThemeData.lerp(null, null, 0), null);
+    const DrawerThemeData data = DrawerThemeData();
+    expect(identical(DrawerThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Default debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const DrawerThemeData().debugFillProperties(builder);

packages/flutter/test/material/dropdown_menu_theme_test.dart

@@ -24,6 +24,12 @@ void main() {
     expect(copy, custom);
   });
 
+  test('DropdownMenuThemeData lerp special cases', () {
+    expect(DropdownMenuThemeData.lerp(null, null, 0), const DropdownMenuThemeData());
+    const DropdownMenuThemeData data = DropdownMenuThemeData();
+    expect(identical(DropdownMenuThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Default DropdownMenuThemeData debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const DropdownMenuThemeData().debugFillProperties(builder);

packages/flutter/test/material/elevated_button_theme_test.dart

@@ -6,6 +6,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('ElevatedButtonThemeData lerp special cases', () {
+    expect(ElevatedButtonThemeData.lerp(null, null, 0), null);
+    const ElevatedButtonThemeData data = ElevatedButtonThemeData();
+    expect(identical(ElevatedButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no ElevatedButtonTheme returns defaults', (WidgetTester tester) async {
     const ColorScheme colorScheme = ColorScheme.light();
     await tester.pumpWidget(

packages/flutter/test/material/expansion_tile_theme_test.dart

@@ -47,6 +47,12 @@ void main() {
     expect(const ExpansionTileThemeData().hashCode, const ExpansionTileThemeData().copyWith().hashCode);
   });
 
+  test('ExpansionTileThemeData lerp special cases', () {
+    expect(ExpansionTileThemeData.lerp(null, null, 0), null);
+    const ExpansionTileThemeData data = ExpansionTileThemeData();
+    expect(identical(ExpansionTileThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('ExpansionTileThemeData defaults', () {
     const ExpansionTileThemeData theme = ExpansionTileThemeData();
     expect(theme.backgroundColor, null);

packages/flutter/test/material/filled_button_theme_test.dart

@@ -6,6 +6,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('FilledButtonThemeData lerp special cases', () {
+    expect(FilledButtonThemeData.lerp(null, null, 0), null);
+    const FilledButtonThemeData data = FilledButtonThemeData();
+    expect(identical(FilledButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no FilledButtonTheme returns defaults', (WidgetTester tester) async {
     const ColorScheme colorScheme = ColorScheme.light();
     await tester.pumpWidget(

packages/flutter/test/material/floating_action_button_theme_test.dart

@@ -13,6 +13,12 @@ void main() {
     expect(const FloatingActionButtonThemeData().hashCode, const FloatingActionButtonThemeData().copyWith().hashCode);
   });
 
+  test('FloatingActionButtonThemeData lerp special cases', () {
+    expect(FloatingActionButtonThemeData.lerp(null, null, 0), null);
+    const FloatingActionButtonThemeData data = FloatingActionButtonThemeData();
+    expect(identical(FloatingActionButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Default values are used when no FloatingActionButton or FloatingActionButtonThemeData properties are specified', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(

packages/flutter/test/material/icon_button_theme_test.dart

@@ -6,6 +6,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('IconButtonThemeData lerp special cases', () {
+    expect(IconButtonThemeData.lerp(null, null, 0), null);
+    const IconButtonThemeData data = IconButtonThemeData();
+    expect(identical(IconButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no IconButtonTheme returns defaults', (WidgetTester tester) async {
     const ColorScheme colorScheme = ColorScheme.light();
     await tester.pumpWidget(

packages/flutter/test/material/list_tile_theme_test.dart

@@ -46,11 +46,17 @@ class TestTextState extends State<TestText> {
 }
 
 void main() {
-  test('ListTileThemeData copyWith, ==, hashCode basics', () {
+  test('ListTileThemeData copyWith, ==, hashCode, basics', () {
     expect(const ListTileThemeData(), const ListTileThemeData().copyWith());
     expect(const ListTileThemeData().hashCode, const ListTileThemeData().copyWith().hashCode);
   });
 
+  test('ListTileThemeData lerp special cases', () {
+    expect(ListTileThemeData.lerp(null, null, 0), null);
+    const ListTileThemeData data = ListTileThemeData();
+    expect(identical(ListTileThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('ListTileThemeData defaults', () {
     const ListTileThemeData themeData = ListTileThemeData();
     expect(themeData.dense, null);

packages/flutter/test/material/menu_bar_theme_test.dart

@@ -46,6 +46,12 @@ void main() {
     );
   }
 
+  test('MenuBarThemeData lerp special cases', () {
+    expect(MenuBarThemeData.lerp(null, null, 0), null);
+    const MenuBarThemeData data = MenuBarThemeData();
+    expect(identical(MenuBarThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('theme is honored', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/material/menu_button_theme_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('MenuButtonThemeData lerp special cases', () {
+    expect(MenuButtonThemeData.lerp(null, null, 0), null);
+    const MenuButtonThemeData data = MenuButtonThemeData();
+    expect(identical(MenuButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+}

packages/flutter/test/material/menu_style_test.dart

@@ -35,6 +35,12 @@ void main() {
   }
 
   group('MenuStyle', () {
+    test('MenuStyle lerp special cases', () {
+      expect(MenuStyle.lerp(null, null, 0), null);
+      const MenuStyle data = MenuStyle();
+      expect(identical(MenuStyle.lerp(data, data, 0.5), data), true);
+    });
+
     testWidgets('fixedSize affects geometry', (WidgetTester tester) async {
       await tester.pumpWidget(
         MaterialApp(

packages/flutter/test/material/menu_theme_test.dart

@@ -46,6 +46,12 @@ void main() {
     );
   }
 
+  test('MenuThemeData lerp special cases', () {
+    expect(MenuThemeData.lerp(null, null, 0), null);
+    const MenuThemeData data = MenuThemeData();
+    expect(identical(MenuThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('theme is honored', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/material/navigation_bar_theme_test.dart

@@ -18,6 +18,12 @@ void main() {
     expect(const NavigationBarThemeData().hashCode, const NavigationBarThemeData().copyWith().hashCode);
   });
 
+  test('NavigationBarThemeData lerp special cases', () {
+    expect(NavigationBarThemeData.lerp(null, null, 0), null);
+    const NavigationBarThemeData data = NavigationBarThemeData();
+    expect(identical(NavigationBarThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Default debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const NavigationBarThemeData().debugFillProperties(builder);

packages/flutter/test/material/navigation_drawer_theme_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('NavigationDrawerThemeData copyWith, ==, hashCode, basics', () {
+    expect(const NavigationDrawerThemeData(), const NavigationDrawerThemeData().copyWith());
+    expect(const NavigationDrawerThemeData().hashCode, const NavigationDrawerThemeData().copyWith().hashCode);
+  });
+
+  test('NavigationDrawerThemeData lerp special cases', () {
+    expect(NavigationDrawerThemeData.lerp(null, null, 0), null);
+    const NavigationDrawerThemeData data = NavigationDrawerThemeData();
+    expect(identical(NavigationDrawerThemeData.lerp(data, data, 0.5), data), true);
+  });
+}

packages/flutter/test/material/outlined_button_theme_test.dart

@@ -6,6 +6,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('OutlinedButtonThemeData lerp special cases', () {
+    expect(OutlinedButtonThemeData.lerp(null, null, 0), null);
+    const OutlinedButtonThemeData data = OutlinedButtonThemeData();
+    expect(identical(OutlinedButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no OutlinedButtonTheme returns defaults', (WidgetTester tester) async {
     const ColorScheme colorScheme = ColorScheme.light();
     await tester.pumpWidget(

packages/flutter/test/material/popup_menu_theme_test.dart

@@ -50,6 +50,12 @@ void main() {
     expect(const PopupMenuThemeData().hashCode, const PopupMenuThemeData().copyWith().hashCode);
   });
 
+  test('PopupMenuThemeData lerp special cases', () {
+    expect(PopupMenuThemeData.lerp(null, null, 0), null);
+    const PopupMenuThemeData data = PopupMenuThemeData();
+    expect(identical(PopupMenuThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('PopupMenuThemeData null fields by default', () {
     const PopupMenuThemeData popupMenuTheme = PopupMenuThemeData();
     expect(popupMenuTheme.color, null);

packages/flutter/test/material/progress_indicator_theme_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('ProgressIndicatorThemeData copyWith, ==, hashCode, basics', () {
+    expect(const ProgressIndicatorThemeData(), const ProgressIndicatorThemeData().copyWith());
+    expect(const ProgressIndicatorThemeData().hashCode, const ProgressIndicatorThemeData().copyWith().hashCode);
+  });
+
+  test('ProgressIndicatorThemeData lerp special cases', () {
+    expect(ProgressIndicatorThemeData.lerp(null, null, 0), null);
+    const ProgressIndicatorThemeData data = ProgressIndicatorThemeData();
+    expect(identical(ProgressIndicatorThemeData.lerp(data, data, 0.5), data), true);
+  });
+}

packages/flutter/test/material/radio_theme_test.dart

@@ -15,6 +15,12 @@ void main() {
     expect(const RadioThemeData().hashCode, const RadioThemeData().copyWith().hashCode);
   });
 
+  test('RadioThemeData lerp special cases', () {
+    expect(RadioThemeData.lerp(null, null, 0), const RadioThemeData());
+    const RadioThemeData data = RadioThemeData();
+    expect(identical(RadioThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('RadioThemeData defaults', () {
     const RadioThemeData themeData = RadioThemeData();
     expect(themeData.mouseCursor, null);

packages/flutter/test/material/scrollbar_theme_test.dart

@@ -25,6 +25,12 @@ void main() {
     expect(const ScrollbarThemeData().hashCode, const ScrollbarThemeData().copyWith().hashCode);
   });
 
+  test('ScrollbarThemeData lerp special cases', () {
+    expect(ScrollbarThemeData.lerp(null, null, 0), const ScrollbarThemeData());
+    const ScrollbarThemeData data = ScrollbarThemeData();
+    expect(identical(ScrollbarThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no ScrollbarTheme returns defaults', (WidgetTester tester) async {
     final ScrollController scrollController = ScrollController();
     await tester.pumpWidget(

packages/flutter/test/material/segmented_button_theme_test.dart

@@ -23,6 +23,12 @@ void main() {
     expect(copy, custom);
   });
 
+  test('SegmentedButtonThemeData lerp special cases', () {
+    expect(SegmentedButtonThemeData.lerp(null, null, 0), const SegmentedButtonThemeData());
+    const SegmentedButtonThemeData theme = SegmentedButtonThemeData();
+    expect(identical(SegmentedButtonThemeData.lerp(theme, theme, 0.5), theme), true);
+  });
+
   testWidgets('Default SegmentedButtonThemeData debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const SegmentedButtonThemeData().debugFillProperties(builder);

packages/flutter/test/material/slider_theme_test.dart

@@ -15,6 +15,11 @@ void main() {
     expect(const SliderThemeData().hashCode, const SliderThemeData().copyWith().hashCode);
   });
 
+  test('SliderThemeData lerp special cases', () {
+    const SliderThemeData data = SliderThemeData();
+    expect(identical(SliderThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Default SliderThemeData debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const SliderThemeData().debugFillProperties(builder);

packages/flutter/test/material/snack_bar_theme_test.dart

@@ -12,6 +12,12 @@ void main() {
     expect(const SnackBarThemeData().hashCode, const SnackBarThemeData().copyWith().hashCode);
   });
 
+  test('SnackBarThemeData lerp special cases', () {
+    expect(SnackBarThemeData.lerp(null, null, 0), const SnackBarThemeData());
+    const SnackBarThemeData data = SnackBarThemeData();
+    expect(identical(SnackBarThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('SnackBarThemeData null fields by default', () {
     const SnackBarThemeData snackBarTheme = SnackBarThemeData();
     expect(snackBarTheme.backgroundColor, null);

packages/flutter/test/material/switch_theme_test.dart

@@ -15,6 +15,11 @@ void main() {
     expect(const SwitchThemeData().hashCode, const SwitchThemeData().copyWith().hashCode);
   });
 
+  test('SwitchThemeData lerp special cases', () {
+    const SwitchThemeData data = SwitchThemeData();
+    expect(identical(SwitchThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('SwitchThemeData defaults', () {
     const SwitchThemeData themeData = SwitchThemeData();
     expect(themeData.thumbColor, null);

packages/flutter/test/material/tab_bar_theme_test.dart

@@ -77,6 +77,11 @@ void main() {
     expect(const TabBarTheme().mouseCursor, null);
   });
 
+  test('TabBarTheme lerp special cases', () {
+    const TabBarTheme theme = TabBarTheme();
+    expect(identical(TabBarTheme.lerp(theme, theme, 0.5), theme), true);
+  });
+
   testWidgets('Tab bar defaults', (WidgetTester tester) async {
     // tests for the default label color and label styles when tabBarTheme and tabBar do not provide any
     await tester.pumpWidget(_withTheme(null, useMaterial3: true));

packages/flutter/test/material/text_button_theme_test.dart

@@ -6,6 +6,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('TextButtonTheme lerp special cases', () {
+    expect(TextButtonThemeData.lerp(null, null, 0), null);
+    const TextButtonThemeData data = TextButtonThemeData();
+    expect(identical(TextButtonThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   testWidgets('Passing no TextButtonTheme returns defaults', (WidgetTester tester) async {
     const ColorScheme colorScheme = ColorScheme.light();
     await tester.pumpWidget(

packages/flutter/test/material/text_selection_theme_test.dart

@@ -14,6 +14,12 @@ void main() {
     expect(const TextSelectionThemeData().hashCode, const TextSelectionThemeData().copyWith().hashCode);
   });
 
+  test('TextSelectionThemeData lerp special cases', () {
+    expect(TextSelectionThemeData.lerp(null, null, 0), null);
+    const TextSelectionThemeData data = TextSelectionThemeData();
+    expect(identical(TextSelectionThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('TextSelectionThemeData null fields by default', () {
     const TextSelectionThemeData theme = TextSelectionThemeData();
     expect(theme.cursorColor, null);

packages/flutter/test/material/text_theme_test.dart

@@ -14,6 +14,12 @@ void main() {
     expect(const TextTheme(), equals(const TextTheme().copyWith()));
   });
 
+  test('TextTheme lerp special cases', () {
+    expect(TextTheme.lerp(null, null, 0), const TextTheme());
+    const TextTheme theme = TextTheme();
+    expect(identical(TextTheme.lerp(theme, theme, 0.5), theme), true);
+  });
+
   test('TextTheme copyWith apply, merge basics with Typography.black', () {
     final Typography typography = Typography.material2018();
     expect(typography.black, equals(typography.black.copyWith()));

packages/flutter/test/material/time_picker_theme_test.dart

@@ -14,6 +14,11 @@ void main() {
     expect(const TimePickerThemeData().hashCode, const TimePickerThemeData().copyWith().hashCode);
   });
 
+  test('TimePickerThemeData lerp special cases', () {
+    const TimePickerThemeData data = TimePickerThemeData();
+    expect(identical(TimePickerThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('TimePickerThemeData null fields by default', () {
     const TimePickerThemeData timePickerTheme = TimePickerThemeData();
     expect(timePickerTheme.backgroundColor, null);

packages/flutter/test/material/toggle_buttons_theme_test.dart

@@ -22,6 +22,12 @@ void main() {
     expect(const ToggleButtonsThemeData().hashCode, const ToggleButtonsThemeData().copyWith().hashCode);
   });
 
+  test('ToggleButtonsThemeData lerp special cases', () {
+    expect(ToggleButtonsThemeData.lerp(null, null, 0), null);
+    const ToggleButtonsThemeData data = ToggleButtonsThemeData();
+    expect(identical(ToggleButtonsThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('ToggleButtonsThemeData defaults', () {
     const ToggleButtonsThemeData themeData = ToggleButtonsThemeData();
     expect(themeData.textStyle, null);

packages/flutter/test/material/tooltip_theme_test.dart

@@ -37,6 +37,12 @@ void main() {
     expect(const TooltipThemeData().hashCode, const TooltipThemeData().copyWith().hashCode);
   });
 
+  test('TooltipThemeData lerp special cases', () {
+    expect(TooltipThemeData.lerp(null, null, 0), null);
+    const TooltipThemeData data = TooltipThemeData();
+    expect(identical(TooltipThemeData.lerp(data, data, 0.5), data), true);
+  });
+
   test('TooltipThemeData defaults', () {
     const TooltipThemeData theme = TooltipThemeData();
     expect(theme.height, null);

packages/flutter/test/material/typography_test.dart

@@ -16,6 +16,11 @@ void main() {
     }
   });
 
+  test('Typography lerp special cases', () {
+    final Typography typography = Typography();
+    expect(identical(Typography.lerp(typography, typography, 0.5), typography), true);
+  });
+
   test('Typography on non-Apple platforms defaults to the correct font', () {
     expect(Typography.material2018().black.titleLarge!.fontFamily, 'Roboto');
     expect(Typography.material2018(platform: TargetPlatform.fuchsia).black.titleLarge!.fontFamily, 'Roboto');