govoplan-core/webui/tests/data-grid-sizing.test.ts

import {
  dataGridLayoutSignature,
  dataGridWidthsForLayout,
  distributeDataGridResizeAmount,
  effectiveDataGridColumnMinWidth,
  fitDataGridColumns,
  type DataGridSizingColumn
} from "../src/components/table/dataGridSizing";

function assertEqual<T>(actual: T, expected: T, message: string): void {
  if (actual !== expected) throw new Error(`${message}: expected ${String(expected)}, got ${String(actual)}`);
}

function assertWidths(
  actual: Record<string, number>,
  expected: Record<string, number>,
  message: string
): void {
  for (const [columnId, width] of Object.entries(expected)) {
    assertEqual(actual[columnId], width, `${message} (${columnId})`);
  }
}

const minmaxColumn: DataGridSizingColumn = {
  id: "recipients",
  width: "minmax(320px, 1.4fr)",
  resizable: true,
  sortable: true,
  filterable: true
};
assertEqual(
  effectiveDataGridColumnMinWidth(minmaxColumn),
  320,
  "a minmax lower bound remains the resize minimum"
);

const weightedColumns: DataGridSizingColumn[] = [
  { id: "fixed", width: 100 },
  { id: "primary", width: "minmax(100px, 1fr)", minWidth: 100, maxWidth: 500 },
  { id: "secondary", width: "minmax(100px, 2fr)", minWidth: 100, maxWidth: 500 }
];
const weightedLayout = fitDataGridColumns(weightedColumns, 600);
assertWidths(
  weightedLayout.widths,
  { fixed: 100, primary: 200, secondary: 300 },
  "fraction tracks receive residual width by declared weight"
);
assertEqual(weightedLayout.bufferWidth, 0, "fraction tracks cover the available container");

const boundedLayout = fitDataGridColumns([
  { id: "fixed", width: 100 },
  { id: "primary", width: "minmax(100px, 1fr)", minWidth: 100, maxWidth: 150 },
  { id: "secondary", width: "minmax(100px, 2fr)", minWidth: 100, maxWidth: 200 }
], 600);
assertWidths(
  boundedLayout.widths,
  { fixed: 100, primary: 150, secondary: 200 },
  "fraction tracks stop at their declared maxima"
);
assertEqual(boundedLayout.bufferWidth, 150, "space beyond column maxima becomes the synthetic buffer");

const overflowLayout = fitDataGridColumns([
  { id: "fixed", width: 200 },
  { id: "primary", width: "minmax(320px, 1fr)", resizable: true },
  { id: "secondary", width: "minmax(260px, 1fr)", resizable: true }
], 600);
assertWidths(
  overflowLayout.widths,
  { fixed: 200, primary: 320, secondary: 260 },
  "columns never shrink below declared minima"
);
assertEqual(overflowLayout.overflowWidth, 180, "minimum-width excess remains horizontal overflow");

const percentageLayout = fitDataGridColumns([
  { id: "fixed", width: 100 },
  { id: "primary", width: "30%", minWidth: 100 },
  { id: "secondary", width: "20%", minWidth: 100 }
], 1000);
assertWidths(
  percentageLayout.widths,
  { fixed: 100, primary: 300, secondary: 200 },
  "percentage tracks retain their preferred container share"
);
assertEqual(percentageLayout.bufferWidth, 400, "unused percentage space remains a neutral buffer");

const overriddenLayout = fitDataGridColumns(weightedColumns, 800, {}, { primary: 450 });
assertWidths(
  overriddenLayout.widths,
  { fixed: 100, primary: 450, secondary: 250 },
  "a user-resized track stays fixed while responsive peers absorb container changes"
);

const overriddenOverflowLayout = fitDataGridColumns(weightedColumns, 500, {}, { primary: 450 });
assertWidths(
  overriddenOverflowLayout.widths,
  { fixed: 100, primary: 450, secondary: 100 },
  "a narrow viewport preserves the user override without squashing peers below their minima"
);
assertEqual(
  overriddenOverflowLayout.overflowWidth,
  150,
  "a user override that cannot fit becomes horizontal overflow"
);

const clampedOverrideLayout = fitDataGridColumns(weightedColumns, 800, {}, { primary: 900 });
assertEqual(
  clampedOverrideLayout.widths.primary,
  500,
  "user overrides remain bounded by the column maximum"
);

const redistributedGrowth = distributeDataGridResizeAmount(300, [
  { columnId: "bounded", startWidth: 100, minWidth: 100, maxWidth: 150, weight: 1 },
  { columnId: "remaining", startWidth: 100, minWidth: 100, maxWidth: 500, weight: 1 }
]);
assertWidths(
  redistributedGrowth.amounts,
  { bounded: 50, remaining: 250 },
  "unused growth is redistributed after a peer reaches its maximum"
);
assertEqual(redistributedGrowth.applied, 300, "bounded weighted growth applies the complete available amount");

const boundedShrink = distributeDataGridResizeAmount(-300, [
  { columnId: "primary", startWidth: 300, minWidth: 200, maxWidth: 500, weight: 1 },
  { columnId: "secondary", startWidth: 300, minWidth: 250, maxWidth: 500, weight: 1 }
]);
assertWidths(
  boundedShrink.amounts,
  { primary: -100, secondary: -50 },
  "shrink distribution stops every peer at its minimum"
);
assertEqual(boundedShrink.applied, -150, "unavailable shrink remains unapplied instead of squashing columns");

const legacyFillLayout = fitDataGridColumns([
  { id: "fixed", width: 100 },
  { id: "fill", width: 200, minWidth: 120, maxWidth: 450, fill: true }
], 500);
assertWidths(
  legacyFillLayout.widths,
  { fixed: 100, fill: 400 },
  "legacy fill columns remain stable under the explicit sizing contract"
);

const originalSignature = dataGridLayoutSignature(weightedColumns, "container", "cover");
const changedSignature = dataGridLayoutSignature(
  weightedColumns.map((column) => column.id === "primary" ? { ...column, maxWidth: 420 } : column),
  "container",
  "cover"
);
assertEqual(
  dataGridWidthsForLayout(originalSignature, originalSignature, { primary: 450 })?.primary,
  450,
  "matching layout signatures restore user widths"
);
assertEqual(
  dataGridWidthsForLayout(originalSignature, changedSignature, { primary: 450 }),
  undefined,
  "stale layout signatures discard user widths"
);
assertEqual(
  dataGridLayoutSignature(weightedColumns, "container", "free") === originalSignature,
  false,
  "free and cover layouts keep independent user overrides"
);