Default colorScheme data in ButtonThemeData (Fix for #38655) (#39627)

* Set default colorScheme for ButtonThemeData

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

@@ -83,7 +83,7 @@ class ButtonTheme extends InheritedTheme {
     Color hoverColor,
     Color highlightColor,
     Color splashColor,
-    ColorScheme colorScheme,
+    ColorScheme colorScheme = const ColorScheme.light(),
     MaterialTapTargetSize materialTapTargetSize,
     Widget child,
   }) : assert(textTheme != null),
@@ -91,6 +91,7 @@ class ButtonTheme extends InheritedTheme {
        assert(height != null && height >= 0.0),
        assert(alignedDropdown != null),
        assert(layoutBehavior != null),
+       assert(colorScheme != null),
        data = ButtonThemeData(
          textTheme: textTheme,
          minWidth: minWidth,
@@ -179,13 +180,14 @@ class ButtonTheme extends InheritedTheme {
     Color hoverColor,
     Color highlightColor,
     Color splashColor,
-    ColorScheme colorScheme,
+    ColorScheme colorScheme = const ColorScheme.light(),
     Widget child,
     ButtonBarLayoutBehavior layoutBehavior = ButtonBarLayoutBehavior.padded,
   }) : assert(textTheme != null),
        assert(minWidth != null && minWidth >= 0.0),
        assert(height != null && height >= 0.0),
        assert(alignedDropdown != null),
+       assert(colorScheme != null),
        data = ButtonThemeData(
          textTheme: textTheme,
          minWidth: minWidth,
@@ -217,15 +219,13 @@ class ButtonTheme extends InheritedTheme {
   static ButtonThemeData of(BuildContext context) {
     final ButtonTheme inheritedButtonTheme = context.inheritFromWidgetOfExactType(ButtonTheme);
     ButtonThemeData buttonTheme = inheritedButtonTheme?.data;
-    if (buttonTheme?.colorScheme == null) { // if buttonTheme or buttonTheme.colorScheme is null
+    if (buttonTheme == null) {
       final ThemeData theme = Theme.of(context);
       buttonTheme ??= theme.buttonTheme;
-      if (buttonTheme.colorScheme == null) {
-        buttonTheme = buttonTheme.copyWith(
-          colorScheme: theme.buttonTheme.colorScheme ?? theme.colorScheme,
-        );
-        assert(buttonTheme.colorScheme != null);
-      }
+      buttonTheme = buttonTheme.copyWith(
+        colorScheme: theme.buttonTheme.colorScheme ?? const ColorScheme.light(),
+      );
+      assert(buttonTheme.colorScheme != null);
     }
     return buttonTheme;
   }
@@ -270,13 +270,14 @@ class ButtonThemeData extends Diagnosticable {
     Color hoverColor,
     Color highlightColor,
     Color splashColor,
-    this.colorScheme,
+    this.colorScheme = const ColorScheme.light(),
     MaterialTapTargetSize materialTapTargetSize,
   }) : assert(textTheme != null),
        assert(minWidth != null && minWidth >= 0.0),
        assert(height != null && height >= 0.0),
        assert(alignedDropdown != null),
        assert(layoutBehavior != null),
+       assert(colorScheme != null),
        _buttonColor = buttonColor,
        _disabledColor = disabledColor,
        _focusColor = focusColor,

packages/flutter/test/material/button_theme_test.dart

@@ -18,6 +18,7 @@ void main() {
     ));
     expect(theme.alignedDropdown, false);
     expect(theme.layoutBehavior, ButtonBarLayoutBehavior.padded);
+    expect(theme.colorScheme, const ColorScheme.light());
   });
 
   test('ButtonThemeData default overrides', () {
@@ -28,12 +29,14 @@ void main() {
       padding: EdgeInsets.zero,
       shape: RoundedRectangleBorder(),
       alignedDropdown: true,
+      colorScheme: ColorScheme.dark()
     );
     expect(theme.textTheme, ButtonTextTheme.primary);
     expect(theme.constraints, const BoxConstraints(minWidth: 100.0, minHeight: 200.0));
     expect(theme.padding, EdgeInsets.zero);
     expect(theme.shape, const RoundedRectangleBorder());
     expect(theme.alignedDropdown, true);
+    expect(theme.colorScheme, const ColorScheme.dark());
   });
 
   testWidgets('ButtonTheme defaults', (WidgetTester tester) async {
@@ -80,7 +83,7 @@ void main() {
       borderRadius: BorderRadius.all(Radius.circular(2.0)),
     ));
     expect(alignedDropdown, false);
-    expect(colorScheme, ThemeData.light().colorScheme);
+    expect(colorScheme, const ColorScheme.light());
     expect(tester.widget<Material>(find.byType(Material)).shape, shape);
     expect(tester.getSize(find.byType(Material)), const Size(88.0, 36.0));
   });
@@ -95,7 +98,7 @@ void main() {
       borderRadius: BorderRadius.all(Radius.circular(2.0)),
     ));
     expect(theme.alignedDropdown, false);
-    expect(theme.colorScheme, null);
+    expect(theme.colorScheme, const ColorScheme.light());
 
     theme = const ButtonThemeData().copyWith(
       textTheme: ButtonTextTheme.primary,
@@ -402,4 +405,80 @@ void main() {
   },
     semanticsEnabled: true,
   );
+
+  testWidgets('Default RaisedButton text color when textTheme is set to ButtonTextTheme.accent', (WidgetTester tester) async {
+    // Test for https://github.com/flutter/flutter/issues/38655
+    const Color defaultEnabledAccentTextColor = Color(0xff2196f3);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: Center(
+            child: RaisedButton(
+              child: const Text('RaisedButton'),
+              onPressed: () {},
+              textTheme: ButtonTextTheme.accent,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    Color getRaisedButtonTextColor() {
+      return tester.renderObject<RenderParagraph>(find.text('RaisedButton')).text.style.color;
+    }
+
+    expect(getRaisedButtonTextColor(), equals(defaultEnabledAccentTextColor));
+  });
+
+  testWidgets('default button theme primary color for RaisedButton', (WidgetTester tester) async {
+    // Test for https://github.com/flutter/flutter/issues/38655
+    const Color defaultEnabledPrimaryTextColor = Color(0xff000000);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: Center(
+            child: RaisedButton(
+              child: const Text('RaisedButton'),
+              onPressed: () {},
+              textTheme: ButtonTextTheme.primary,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    Color getRaisedButtonTextColor() {
+      return tester.renderObject<RenderParagraph>(find.text('RaisedButton')).text.style.color;
+    }
+
+    expect(getRaisedButtonTextColor(), equals(defaultEnabledPrimaryTextColor));
+  });
+
+  testWidgets('default button theme normal color for RaisedButton', (WidgetTester tester) async {
+    // Test for https://github.com/flutter/flutter/issues/38655
+    const Color defaultEnabledNormalTextColor = Color(0xffffffff);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        theme: ThemeData.dark(),
+        home: Scaffold(
+          body: Center(
+            child: RaisedButton(
+              child: const Text('RaisedButton'),
+              onPressed: () {},
+              textTheme: ButtonTextTheme.normal
+            ),
+          ),
+        ),
+      ),
+    );
+
+    Color getRaisedButtonTextColor() {
+      return tester.renderObject<RenderParagraph>(find.text('RaisedButton')).text.style.color;
+    }
+
+    expect(getRaisedButtonTextColor(), equals(defaultEnabledNormalTextColor));
+  });
 }