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Prevent exception when creating a Divider borderSide (#39572)

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rami-a 2019-09-03 10:15:42 -04:00 committed by GitHub
parent 16fcb83fec
commit 0ebcfe10da
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2 changed files with 31 additions and 7 deletions
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31
packages/flutter/lib/src/material/divider.dart
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@ -91,12 +91,16 @@ class Divider extends StatelessWidget {
/// {@end-tool}
final Color color;
/// Computes the [BorderSide] that represents a divider of the specified
/// color, or, if there is no specified color, of the default
/// [ThemeData.dividerColor] specified in the ambient [Theme].
/// Computes the [BorderSide] that represents a divider..
///
/// The `width` argument can be used to override the default width of the
/// divider border, which defaults to 0.0 (a hairline border).
/// If [color] is null, then [DividerThemeData.color] is used. If that is also
/// null, then [ThemeData.dividerColor] is used.
///
/// If [width] is null, then [DividerThemeData.thickness] is used. If that is
/// also null, then this defaults to 0.0 (a hairline border).
///
/// If [context] is null, the default color of [BorderSide] is used and the
/// default width of 0.0 is used.
///
/// {@tool sample}
///
@ -117,9 +121,22 @@ class Divider extends StatelessWidget {
/// ```
/// {@end-tool}
static BorderSide createBorderSide(BuildContext context, { Color color, double width }) {
final Color effectiveColor = color
?? (context != null ? (DividerTheme.of(context).color ?? Theme.of(context).dividerColor) : null);
final double effectiveWidth = width
?? (context != null ? DividerTheme.of(context).thickness : null)
?? 0.0;
// Prevent assertion since it is possible that context is null and no color
// is specified.
if (effectiveColor == null) {
return BorderSide(
width: effectiveWidth,
);
}
return BorderSide(
color: color ?? DividerTheme.of(context).color ?? Theme.of(context).dividerColor,
width: width ?? DividerTheme.of(context).thickness ?? 0.0,
color: effectiveColor,
width: effectiveWidth,
);
}

7
packages/flutter/test/material/divider_test.dart
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@ -203,4 +203,11 @@ void main() {
expect(lineRect.top, dividerRect.top + customIndent);
expect(lineRect.bottom, dividerRect.bottom - customIndent);
});
// Regression test for https://github.com/flutter/flutter/issues/39533
testWidgets('createBorderSide does not throw exception with null context', (WidgetTester tester) async {
// Passing a null context used to throw an exception but no longer does.
expect(() => Divider.createBorderSide(null), isNot(throwsAssertionError));
expect(() => Divider.createBorderSide(null), isNot(throwsNoSuchMethodError));
});
}