Test

test/chart/bar_chart/bar_chart_alignment_widget_test.dart

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+import 'package:fl_chart/fl_chart.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+List<BarChartGroupData> get barGroups => [
+      BarChartGroupData(x: 0, barRods: [BarChartRodData(toY: 8)]),
+      BarChartGroupData(x: 1, barRods: [BarChartRodData(toY: 10)]),
+      BarChartGroupData(x: 2, barRods: [BarChartRodData(toY: 14)]),
+      BarChartGroupData(x: 3, barRods: [BarChartRodData(toY: 15)]),
+      BarChartGroupData(x: 4, barRods: [BarChartRodData(toY: 13)]),
+      BarChartGroupData(x: 5, barRods: [BarChartRodData(toY: 10)]),
+      BarChartGroupData(x: 6, barRods: [BarChartRodData(toY: 16)]),
+      BarChartGroupData(x: 7, barRods: [BarChartRodData(toY: 8)]),
+      BarChartGroupData(x: 8, barRods: [BarChartRodData(toY: 10)]),
+      BarChartGroupData(x: 9, barRods: [BarChartRodData(toY: 14)]),
+      BarChartGroupData(x: 10, barRods: [BarChartRodData(toY: 15)]),
+      BarChartGroupData(x: 11, barRods: [BarChartRodData(toY: 13)]),
+      BarChartGroupData(x: 12, barRods: [BarChartRodData(toY: 10)]),
+      BarChartGroupData(x: 13, barRods: [BarChartRodData(toY: 16)]),
+      BarChartGroupData(x: 14, barRods: [BarChartRodData(toY: 8)]),
+      BarChartGroupData(x: 15, barRods: [BarChartRodData(toY: 10)]),
+      BarChartGroupData(x: 16, barRods: [BarChartRodData(toY: 14)]),
+      BarChartGroupData(x: 17, barRods: [BarChartRodData(toY: 15)]),
+      BarChartGroupData(x: 18, barRods: [BarChartRodData(toY: 13)]),
+      BarChartGroupData(x: 19, barRods: [BarChartRodData(toY: 10)]),
+      BarChartGroupData(x: 20, barRods: [BarChartRodData(toY: 16)]),
+    ];
+
+void main() {
+  const viewSize = Size(400, 400);
+
+  testWidgets(
+    'Barchart alignment overflow test',
+    (WidgetTester tester) async {
+      // Test that the bar chart alignment works as expected when the
+      // bar groups are too wide to fit in the chart.
+      for (final groupsSpace in [4.0, 20.0]) {
+        for (final barChartAlignment in [
+          BarChartAlignment.start,
+          BarChartAlignment.center,
+          BarChartAlignment.end,
+        ]) {
+          // Build the bar chart.
+          await tester.pumpWidget(
+            MaterialApp(
+              home: Scaffold(
+                body: Center(
+                  child: SizedBox(
+                    width: viewSize.width,
+                    height: viewSize.height,
+                    child: BarChart(
+                      BarChartData(
+                        barGroups: barGroups,
+                        gridData: const FlGridData(show: false),
+                        alignment: barChartAlignment,
+                        groupsSpace: groupsSpace,
+                        maxY: 20,
+                      ),
+                    ),
+                  ),
+                ),
+              ),
+            ),
+          );
+
+          // Wait for the chart to be rendered.
+          await tester.pumpAndSettle();
+
+          // Take a golden image.
+          final fname = '${barChartAlignment}_$groupsSpace';
+          await expectLater(
+            find.byType(BarChart),
+            matchesGoldenFile('golden/$fname.png'),
+          );
+        }
+      }
+    },
+  );
+}