grain.social/grain-ios
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@testable import Grain
import SwiftUI
import XCTest
/// The gallery editor morphs one set of cells between a strip, a grid and a
/// captions list, and drag-to-reorder shuffles slots underneath that. All three
/// layouts and the slot maths are value types, so they can be checked directly
/// rather than by eye.
@MainActor
final class EditorLayoutTests: GrainTestCase {
private let width: CGFloat = 402
/// 402 - 2*16 outer padding - 2*4 spacing, over three columns.
private var gridCellSide: CGFloat {
(402 - 32 - 8) / 3
}
/// Height `AdaptivePhotoLayout` reports for `count` cells in `mode`.
private func layoutHeight(mode: EditorMode, count: Int) -> CGFloat {
let layout = AdaptivePhotoLayout(mode: mode, containerWidth: width)
let view = layout {
ForEach(0 ..< count, id: \.self) { index in
Color.gray
.frame(height: 40)
.layoutValue(key: PhotoIndexKey.self, value: index)
}
}
return UIHostingController(rootView: view)
.sizeThatFits(in: CGSize(width: width, height: .greatestFiniteMagnitude))
.height
}
// MARK: - AdaptivePhotoLayout sizing
/// The strip is one row of 72pt thumbs however many photos there are —
/// that fixed height is what stops the form jumping as photos are added.
func testTheStripIsOneFixedHeightRowRegardlessOfCount() {
let expected: CGFloat = 72 + 22 * 2
XCTAssertEqual(layoutHeight(mode: .preview, count: 1), expected, accuracy: 0.5)
XCTAssertEqual(layoutHeight(mode: .preview, count: 9), expected, accuracy: 0.5)
}
func testTheGridGrowsARowAtATime() {
let oneRow = layoutHeight(mode: .reorder, count: 3)
let twoRows = layoutHeight(mode: .reorder, count: 4)
let stillTwoRows = layoutHeight(mode: .reorder, count: 6)
XCTAssertEqual(twoRows, stillTwoRows, accuracy: 0.5, "Four and six photos are both two rows")
XCTAssertEqual(twoRows - oneRow, gridCellSide + 4, accuracy: 0.5, "A new row should cost a cell plus its spacing")
}
func testTheGridIsACellPlusItsPaddingForASingleRow() {
// One row of cells, 22pt above and 12pt below.
XCTAssertEqual(layoutHeight(mode: .reorder, count: 2), gridCellSide + 34, accuracy: 0.5)
}
func testTheCaptionsListStacksEveryRow() {
let one = layoutHeight(mode: .captions, count: 1)
let three = layoutHeight(mode: .captions, count: 3)
XCTAssertEqual(three, one * 3, accuracy: 0.5, "Captions rows should simply stack")
// 40pt of content plus 10pt above and below.
XCTAssertEqual(one, 60, accuracy: 0.5)
}
/// Every mode is asked to size before there is anything to show.
func testAnEmptyEditorHasNoHeightInAnyMode() {
for mode in EditorMode.allCases {
XCTAssertEqual(layoutHeight(mode: mode, count: 0), 0, accuracy: 0.5, "\(mode.label) sized a non-empty box")
}
}
/// Switching modes is an animated interpolation between two layouts, so the
/// three have to disagree — otherwise nothing moves.
func testTheThreeModesReportDifferentHeights() {
let heights = EditorMode.allCases.map { layoutHeight(mode: $0, count: 5) }
XCTAssertEqual(Set(heights.map { Int($0.rounded()) }).count, 3, "Two modes size identically: \(heights)")
}
// MARK: - EditorMode
func testEveryModeHasALabel() {
XCTAssertEqual(EditorMode.preview.label, "Preview")
XCTAssertEqual(EditorMode.reorder.label, "Reorder")
XCTAssertEqual(EditorMode.captions.label, "Alt text")
XCTAssertEqual(EditorMode.allCases.count, 3)
}
// MARK: - CellGeometry
/// In the strip and the captions list the photo fills the square mask and
/// overflows on its long edge; in the grid it fits inside instead.
func testAWidePhotoOverflowsTheMaskInTheStripAndFitsItInTheGrid() {
let wide: CGFloat = 3.0 / 2.0
let strip = CellGeometry(mode: .preview, maskSide: 72, photoAspect: wide).photoSize
XCTAssertEqual(strip.height, 72, accuracy: 0.01)
XCTAssertGreaterThan(strip.width, 72)
let grid = CellGeometry(mode: .reorder, maskSide: 72, photoAspect: wide).photoSize
XCTAssertEqual(grid.width, 72, accuracy: 0.01)
XCTAssertLessThan(grid.height, 72)
}
func testATallPhotoMirrorsTheWideCase() {
let tall: CGFloat = 2.0 / 3.0
let strip = CellGeometry(mode: .preview, maskSide: 72, photoAspect: tall).photoSize
XCTAssertEqual(strip.width, 72, accuracy: 0.01)
XCTAssertGreaterThan(strip.height, 72)
let grid = CellGeometry(mode: .reorder, maskSide: 72, photoAspect: tall).photoSize
XCTAssertEqual(grid.height, 72, accuracy: 0.01)
XCTAssertLessThan(grid.width, 72)
}
func testASquarePhotoIsTheMaskInEveryMode() {
for mode in EditorMode.allCases {
let size = CellGeometry(mode: mode, maskSide: 72, photoAspect: 1).photoSize
XCTAssertEqual(size.width, 72, accuracy: 0.01, "\(mode.label) stretched a square photo")
XCTAssertEqual(size.height, 72, accuracy: 0.01, "\(mode.label) stretched a square photo")
}
}
func testCaptionsUseTheSameFillAsTheStrip() {
let wide: CGFloat = 3.0 / 2.0
XCTAssertEqual(
CellGeometry(mode: .captions, maskSide: 60, photoAspect: wide).photoSize,
CellGeometry(mode: .preview, maskSide: 60, photoAspect: wide).photoSize
)
}
/// The grid is edge-to-edge, so its cells square off while the others stay
/// rounded.
func testOnlyTheGridSquaresOffItsCorners() {
XCTAssertEqual(CellGeometry(mode: .reorder, maskSide: 72, photoAspect: 1).maskCornerRadius, 0)
XCTAssertEqual(CellGeometry(mode: .preview, maskSide: 72, photoAspect: 1).maskCornerRadius, 8)
XCTAssertEqual(CellGeometry(mode: .captions, maskSide: 60, photoAspect: 1).maskCornerRadius, 8)
}
// MARK: - ReorderDragState
private func draggingState(from index: Int) -> ReorderDragState {
let state = ReorderDragState()
state.beginDrag(itemID: UUID(), at: index)
return state
}
private let cellStride = CGSize(width: 124, height: 124)
func testBeginningADragRecordsWhereItStarted() {
let state = draggingState(from: 2)
XCTAssertTrue(state.isDragging)
XCTAssertEqual(state.dragStartIndex, 2)
XCTAssertEqual(state.dragCurrentIndex, 2)
}
/// A second gesture arriving mid-drag must not retarget the one in flight.
func testASecondDragIsIgnoredWhileOneIsRunning() {
let state = draggingState(from: 2)
state.beginDrag(itemID: UUID(), at: 5)
XCTAssertEqual(state.dragStartIndex, 2)
}
func testResettingClearsEverything() {
let state = draggingState(from: 2)
state.handleDragChanged(translation: CGSize(width: 124, height: 0), itemCount: 9, columnCount: 3, stride: cellStride)
state.reset()
XCTAssertFalse(state.isDragging)
XCTAssertNil(state.dragStartIndex)
XCTAssertNil(state.dragCurrentIndex)
XCTAssertEqual(state.dragOffset, .zero)
}
func testDraggingOneCellRightProposesTheNextSlot() {
let state = draggingState(from: 0)
let proposed = state.handleDragChanged(
translation: CGSize(width: 124, height: 0), itemCount: 9, columnCount: 3, stride: cellStride
)
XCTAssertEqual(proposed, 1)
XCTAssertEqual(state.dragOffset.width, 124, accuracy: 0.01)
}
func testDraggingOneRowDownProposesTheSlotBelow() {
let state = draggingState(from: 1)
let proposed = state.handleDragChanged(
translation: CGSize(width: 0, height: 124), itemCount: 9, columnCount: 3, stride: cellStride
)
XCTAssertEqual(proposed, 4)
}
/// A cell has to travel past the halfway point before the slot flips, or
/// the grid reshuffles under the finger on every pixel of movement.
func testASmallMovementProposesNothing() {
let state = draggingState(from: 0)
XCTAssertNil(state.handleDragChanged(
translation: CGSize(width: 40, height: 0), itemCount: 9, columnCount: 3, stride: cellStride
))
}
/// Dragging off the left of column one must stay in column one rather than
/// wrapping onto the previous row.
func testDraggingPastTheLeftEdgeStaysInTheFirstColumn() {
let state = draggingState(from: 3)
let proposed = state.handleDragChanged(
translation: CGSize(width: -500, height: 0), itemCount: 9, columnCount: 3, stride: cellStride
)
XCTAssertNil(proposed, "Clamping should leave the cell where it already is")
}
func testDraggingPastTheEndClampsToTheLastSlot() {
let state = draggingState(from: 0)
let proposed = state.handleDragChanged(
translation: CGSize(width: 500, height: 900), itemCount: 5, columnCount: 3, stride: cellStride
)
XCTAssertEqual(proposed, 4)
}
func testDraggingPastTheTopClampsToTheFirstRow() {
let state = draggingState(from: 4)
let proposed = state.handleDragChanged(
translation: CGSize(width: 0, height: -900), itemCount: 9, columnCount: 3, stride: cellStride
)
XCTAssertEqual(proposed, 1)
}
/// Called from a layout that may not have measured yet.
func testADegenerateStrideProposesNothing() {
let state = draggingState(from: 0)
XCTAssertNil(state.handleDragChanged(
translation: CGSize(width: 124, height: 0), itemCount: 9, columnCount: 3, stride: .zero
))
}
func testNoProposalWithoutADragInFlight() {
let state = ReorderDragState()
XCTAssertNil(state.handleDragChanged(
translation: CGSize(width: 124, height: 0), itemCount: 9, columnCount: 3, stride: cellStride
))
XCTAssertFalse(state.isDragging)
}
// MARK: - ReorderDragPlacement
func testPlacementsCompareByBothIndices() {
XCTAssertEqual(
ReorderDragPlacement(draggedIndex: 1, currentIndex: 3),
ReorderDragPlacement(draggedIndex: 1, currentIndex: 3)
)
XCTAssertNotEqual(
ReorderDragPlacement(draggedIndex: 1, currentIndex: 3),
ReorderDragPlacement(draggedIndex: 1, currentIndex: 4)
)
}
}