rzen
9a52b795b2
The right-edge drag's growth was capped at the screen's visible frame, because each snap tick grows the window; on a window near the screen edge that left a lane stuck at a tick or two of headroom. Settled 2026-08-08 (03-board-ui.md § Lane, superseding the pathfinder's hard stop): at the screen the window pins and each further tick re-divides the fixed strip width across one more unit — siblings compress, the stepper's mechanism arriving under the drag's fingers. The regimes meet with no pixel jump (the re-divided standard at the fit IS the frozen standard, by the exact-fill identity), shrinking mirrors the way back, the rubber band moves to the strip's own capacity, and a window with no headroom at all — full screen included — re-divides from the very first snap. New pure arithmetic in LaneLayoutMath (pinnedStripWidth, resizeStandard, resizeMaxUnits, resizeWindowDelta, snappedUnits over per-count slots); LaneResizeSession splits the tick across the regimes and derives its standard from the live count; the handle and BoardView hand the session the strip's whole divide. 2709 unit tests green (+11). Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy
548 lines
27 KiB
Swift
548 lines
27 KiB
Swift
import CoreGraphics
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import Foundation
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import Testing
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@testable import Kanban
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/// Unit tests for the board strip's pure geometry (03-board-ui.md § Layout — full visibility and
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/// § Lane): the resting division of the window across width units, and the right-edge drag's
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/// asymmetric "shadow leads" snap.
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///
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/// Fixture throughout the snap suites: a frozen standard of 100 and a gap of 12 — so a `step`
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/// (`standard + gap`) is 112, and the slot widths are:
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/// 1× = 100 · 2× = 212 · 3× = 324
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/// The tick-up threshold for shadow `k` is `slotWidth(k) + gap` — the far side of the gap trailing
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/// that slot — so 1↔2 ticks up at 112 (100 + 12) and 2↔3 at 224 (212 + 12). The tick-down threshold
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/// back to `k - 1` is `slotWidth(k - 1) + gap - reentry`, 10pt shy of that same boundary — so 2↔1
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/// ticks down at 102 (112 − 10) and 3↔2 at 214 (224 − 10).
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///
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/// Where the pathfinder's twin suite pinned a hard 1…3 width cap, these pin the two regimes the
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/// screen fit divides (03-board-ui.md § Lane, settled 2026-08-08): up to the fit a tick grows the
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/// window, past it a tick re-divides the pinned strip, and `allowedRange`'s ceiling is the strip's
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/// own capacity rather than either — the width field itself has no cap. The suites below take a
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/// screen fit as a *range* where the mechanism is not what is under test, and the re-divide gets its
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/// own suite at the foot of the file.
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private let standard: CGFloat = 100
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private let gap: CGFloat = 12
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private let step: CGFloat = standard + gap // 112
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private let reentry: CGFloat = 10
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/// A screen that fits three units — the drag's ceiling in most tests below.
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private let fitsThree = 1...3
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private func slot(_ units: Int) -> CGFloat {
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LaneLayoutMath.slotWidth(units: units, standard: standard, gap: gap)
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}
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private func snapped(_ liveWidth: CGFloat, current: Int, range: ClosedRange<Int>? = nil) -> Int {
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LaneLayoutMath.snappedUnits(liveWidth: liveWidth, currentUnits: current,
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standard: standard, gap: gap,
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allowedRange: range ?? fitsThree, reentry: reentry)
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}
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// MARK: - Lane fixtures
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/// Loads a board whose lanes carry the given `width:` frontmatter values (`nil` writes no key), in
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/// the order given — `order` keys make the display order the argument order.
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///
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/// Built through `BoardLoader` rather than by constructing `Lane` values by hand: `width`'s
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/// leniency is a *read-side* rule (01-storage-format.md § Frontmatter), so the only honest way to
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/// ask "what does a malformed width display as" is to put the malformed bytes on disk and load
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/// them.
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private func lanes(widths: [String?]) throws -> [Lane] {
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let root = FileManager.default.temporaryDirectory
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.appendingPathComponent("LaneLayoutMathTests-\(UUID().uuidString)", isDirectory: true)
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try FileManager.default.createDirectory(at: root, withIntermediateDirectories: true)
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defer { try? FileManager.default.removeItem(at: root) }
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try write("---\nschema: 1\ntitle: Board\n---\n", to: root)
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for (index, width) in widths.enumerated() {
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var frontmatter = "---\nschema: 1\ntitle: Lane \(index)\norder: \(1024 * (index + 1))\n"
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if let width {
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frontmatter += "width: \(width)\n"
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}
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frontmatter += "---\n"
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let folder = root.appendingPathComponent(UUID().uuidString.lowercased(), isDirectory: true)
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try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
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try write(frontmatter, to: folder)
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}
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return try BoardLoader.load(boardRoot: root).model.lanes
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}
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private func write(_ text: String, to folder: URL) throws {
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try Data(text.utf8).write(to: folder.appendingPathComponent("index.md"))
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}
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private func lane(width: String?) throws -> Lane {
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let loaded = try lanes(widths: [width])
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return try #require(loaded.first)
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}
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// MARK: - The resting layout
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@Suite("LaneLayoutMath ▸ the resting division")
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struct LaneLayoutStandardWidthTests {
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@Test("The strip divides its width across the units, counting a gap outside each end")
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func standardWidthCountsOuterMargins() {
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// 1000 = 1 lane + 2 outer gaps: (1000 − 24) / 1.
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#expect(LaneLayoutMath.standardWidth(stripWidth: 1000, totalUnits: 1, gap: 12) == 976)
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// Three units: 4 gaps (2 interior + 2 outer) → (1000 − 48) / 3.
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#expect(abs(LaneLayoutMath.standardWidth(stripWidth: 1000, totalUnits: 3, gap: 12) - 952.0 / 3.0) < 0.0001)
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// A wide lane consumes several units of the same division, and the strip still fills
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// exactly: 4 units of standard plus the gaps is the whole strip.
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let standard = LaneLayoutMath.standardWidth(stripWidth: 1000, totalUnits: 4, gap: 12)
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let filled = 4 * standard + 12 * 5
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#expect(abs(filled - 1000) < 0.0001)
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}
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@Test("A slot swallows the interior gaps it spans, so lanes and slots are the same pixels")
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func slotWidthSwallowsInteriorGaps() {
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#expect(slot(1) == 100)
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#expect(slot(2) == 212) // 2·100 + 1·12
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#expect(slot(3) == 324) // 3·100 + 2·12
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}
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@Test("Compression is accepted, not floored — only a 1pt floor keeps frames positive")
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func degenerateStripsCompressWithoutAMinimum() {
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// Twenty units in a small window: each lane is a sliver, and that is the design's answer
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// ("the degenerate case is accepted, not floored"), not a scroll bar.
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let squeezed = LaneLayoutMath.standardWidth(stripWidth: 400, totalUnits: 20, gap: 12)
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#expect(squeezed > 0)
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#expect(squeezed < 10)
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// Narrower than its own gaps: still positive, because a zero or negative frame is a
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// rendering bug rather than a design outcome.
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#expect(LaneLayoutMath.standardWidth(stripWidth: 10, totalUnits: 4, gap: 12) == 1)
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#expect(LaneLayoutMath.standardWidth(stripWidth: 0, totalUnits: 1, gap: 12) == 1)
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}
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@Test("An empty strip still has a divisor")
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func zeroUnitsIsTreatedAsOne() {
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#expect(LaneLayoutMath.standardWidth(stripWidth: 1000, totalUnits: 0, gap: 12) == 976)
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#expect(LaneLayoutMath.totalUnits(of: []) == 1)
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}
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}
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// MARK: - Reading a lane's units
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@Suite("LaneLayoutMath ▸ display units")
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struct LaneDisplayUnitsTests {
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@Test("A valid width spans that many units")
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func validWidthSpansItsUnits() throws {
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#expect(LaneLayoutMath.displayUnits(of: try lane(width: "3")) == 3)
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#expect(LaneLayoutMath.displayUnits(of: try lane(width: "1")) == 1)
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// The read side coerces where a sensible reading exists, and the layout follows it.
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#expect(LaneLayoutMath.displayUnits(of: try lane(width: "\"2\"")) == 2)
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}
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@Test("A missing, malformed, zero or negative width renders as one unit")
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func leniencyRendersAsOne() throws {
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let missing = try lane(width: nil)
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#expect(missing.width.isMissing)
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#expect(LaneLayoutMath.displayUnits(of: missing) == 1)
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// A fraction or non-numeric text has no integer reading at all — stays `.malformed` on
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// the model (bytes preserved, not corrected) and renders as 1.
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for raw in ["wide", "1.5"] {
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let lane = try lane(width: raw)
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#expect(lane.width.isMalformed, "width: \(raw) should stay malformed rather than coerce")
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#expect(LaneLayoutMath.displayUnits(of: lane) == 1, "width: \(raw) should render as one unit")
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}
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// An exact integer below 1 is a **different** case (01-storage-format.md § Frontmatter,
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// "ranges are part of the sensible reading", settled): it coerces to `.valid(1)`, not
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// malformed — same on-screen result, different model reading.
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for raw in ["0", "-3"] {
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let lane = try lane(width: raw)
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#expect(lane.width == .valid(1), "width: \(raw) should coerce to 1, not stay malformed")
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#expect(LaneLayoutMath.displayUnits(of: lane) == 1, "width: \(raw) should render as one unit")
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}
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}
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@Test("The strip's unit total is the sum over the lanes it is given")
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func totalUnitsSumsDisplayUnits() throws {
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let loaded = try lanes(widths: ["2", nil, "3", "banana"])
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#expect(loaded.map(LaneLayoutMath.displayUnits(of:)) == [2, 1, 3, 1])
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#expect(LaneLayoutMath.totalUnits(of: loaded) == 7)
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#expect(LaneLayoutMath.totalUnits(of: Array(loaded.prefix(2))) == 3)
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}
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@Test("There is no upper cap on a lane's width")
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func widthIsUncapped() throws {
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// 03-board-ui.md § Lane: "1×, 2×, 3×, … — no cap". A wide lane simply takes more of the
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// division; nothing clamps it on the way in.
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let wide = try lane(width: "40")
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#expect(LaneLayoutMath.displayUnits(of: wide) == 40)
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#expect(LaneLayoutMath.totalUnits(of: [wide]) == 40)
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}
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@Test("The trash's one fixed unit joins the total only while it is shown")
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func trashUnitJoinsTheDivision() throws {
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// 03-board-ui.md § Trash: the quasi-lane "spans a fixed one width unit … consumed only
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// while shown", and Show/Hide Trash is therefore a re-divide trigger — the window is never
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// touched, the same width simply divides across one more unit.
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let loaded = try lanes(widths: ["2", nil, "3"])
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#expect(LaneLayoutMath.totalUnits(of: loaded) == 6)
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#expect(LaneLayoutMath.totalUnits(of: loaded, trashUnits: 1) == 7)
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// Shown on a zero-lane board it is the whole division, not a second unit alongside the
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// empty board's floor of one.
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#expect(LaneLayoutMath.totalUnits(of: [], trashUnits: 1) == 1)
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}
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}
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// MARK: - Hit testing
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/// `laneIndex(atX:…)` — the strip's half of drag-to-restore (03-board-ui.md § Trash). Same lane
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/// geometry as the layout above: standard 100, gap 12, so with lanes of 1× and 2× units the slots
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/// run [12, 112), [124, 336) and everything past 348 is the trash's side of the strip.
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@Suite("LaneLayoutMath ▸ hit testing")
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struct LaneHitTestingTests {
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private let units = [1, 2, 1]
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private func hit(_ x: CGFloat) -> Int? {
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LaneLayoutMath.laneIndex(atX: x, unitCounts: units, standard: 100, gap: 12)
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}
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@Test("A point inside a lane's slot names that lane, width counted in units")
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func insideALaneSlot() {
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#expect(hit(12) == 0)
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#expect(hit(111.9) == 0)
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#expect(hit(124) == 1)
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// The 2× lane swallows the interior gap it spans, so its slot runs 212pt, not 200.
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#expect(hit(335.9) == 1)
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#expect(hit(348) == 2)
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#expect(hit(447.9) == 2)
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}
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@Test("The margins, the gaps, and everything past the last lane name nothing")
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func gapsAndMarginsAreNotLanes() {
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// The outer margin, before the first lane.
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#expect(hit(0) == nil)
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#expect(hit(11.9) == nil)
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// The inter-lane gaps.
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#expect(hit(112) == nil)
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#expect(hit(123.9) == nil)
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#expect(hit(336) == nil)
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// Past the last lane — which is exactly where the trash quasi-lane sits, so a row dropped
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// back into the trash writes nothing.
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#expect(hit(448) == nil)
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#expect(hit(10_000) == nil)
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// A negative x (the pointer dragged off the leading edge) is not a lane either.
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#expect(hit(-5) == nil)
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}
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@Test("An empty strip has no lane under any point")
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func emptyStrip() {
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#expect(LaneLayoutMath.laneIndex(atX: 50, unitCounts: [], standard: 100, gap: 12) == nil)
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}
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}
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// MARK: - The snap
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@Suite("LaneLayoutMath ▸ the drag's snap")
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struct LaneSnapTests {
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// MARK: Tick up — fires just past the far side of the gap, not inside it
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@Test("Ticks up only past the far side of the trailing gap")
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func ticksUpOnlyPastTheFarSideOfTheGap() {
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// Slot 1 is 100; its trailing gap runs to 112 (100 + 12). The shadow must not lead the live
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// edge while the edge is still IN the gap.
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#expect(snapped(111.9, current: 1) == 1) // still inside the gap holds
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#expect(snapped(112, current: 1) == 1) // exactly at the far edge holds (strict >)
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#expect(snapped(112.1, current: 1) == 2) // clearing the gap ticks up immediately
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}
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@Test("Ticks up by exactly one per call")
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func ticksUpByExactlyOne() {
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// A live width well into 3×'s slot still steps only one unit per call (the continuous drag
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// calls this on every event, and the session iterates it to a fixed point).
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#expect(snapped(1000, current: 1) == 2)
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#expect(snapped(1000, current: 2) == 3)
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}
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// MARK: Tick down — fires only 10pt back inside the gap just crossed
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@Test("Ticks down only below the 10pt re-entry point")
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func ticksDownOnlyBelowTheReentryPoint() {
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// Coming back from 2×, the boundary is slot(1) + gap = 112; tick-down requires retreating a
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// further 10pt to 102.
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#expect(snapped(102.1, current: 2) == 2) // just above the re-entry point holds
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#expect(snapped(102, current: 2) == 2) // exactly at the re-entry point holds (strict <)
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#expect(snapped(101.9, current: 2) == 1) // clearing the re-entry point ticks down
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}
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@Test("Re-entering the gap is not enough to tick down")
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func ticksDownDoesNotFireWhileStillInTheGap() {
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// Immediately after re-entering the gap (e.g. 110), the edge has NOT yet retreated the full
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// 10pt, so the shadow must still hold at 2× — this is the asymmetry: growing was instant,
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// shrinking is not.
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#expect(snapped(110, current: 2) == 2)
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#expect(snapped(103, current: 2) == 2)
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}
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// MARK: Hold-band stability from both directions
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@Test("The hold band is stable from both directions")
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func holdBandIsStable() {
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// The hold band for shadow 2× is (102, 224] — everything strictly between the 1↔2 re-entry
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// point and the 2↔3 tick-up threshold holds at 2× with no oscillation.
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for width in stride(from: CGFloat(103), through: 223, by: 20) {
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#expect(snapped(width, current: 2) == 2, "2× holds at \(width)")
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}
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}
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@Test("A value that just ticked up does not immediately tick back down")
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func noImmediateReversalAfterTickingUp() {
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// Crossing 112.1 ticks 1× → 2×. Re-evaluating at that same live width with the NEW unit
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// count must hold, not bounce back — 112.1 is comfortably above the 2↔1 re-entry point.
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let justTicked = snapped(112.1, current: 1)
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#expect(justTicked == 2)
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#expect(snapped(112.1, current: justTicked) == 2)
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}
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@Test("A value that just ticked down does not immediately tick back up")
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func noImmediateReversalAfterTickingDown() {
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let justTicked = snapped(101.9, current: 2)
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#expect(justTicked == 1)
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#expect(snapped(101.9, current: justTicked) == 1)
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}
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// MARK: Range clamping
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@Test("The snap never steps past the allowed range")
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func neverTicksPastTheAllowedRange() {
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#expect(snapped(5000, current: 3) == 3, "the range's ceiling holds")
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#expect(snapped(0, current: 1) == 1, "one unit is the floor")
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#expect(snapped(-500, current: 1) == 1)
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}
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@Test("The range's ceiling is the only ceiling, and it is not a width cap")
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func snapRespectsTheAllowedCeiling() {
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// With the range capped at 2×, no live width ticks to 3×.
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let capsAtTwo = 1...2
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#expect(snapped(1000, current: 2, range: capsAtTwo) == 2)
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#expect(snapped(5000, current: 2, range: capsAtTwo) == 2)
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// Below the cap it still ticks normally.
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#expect(snapped(200, current: 1, range: capsAtTwo) == 2)
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// A roomier ceiling keeps ticking well past the pathfinder's old 3× — Lanework's width has
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// no cap of its own (03-board-ui.md § Lane).
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#expect(snapped(5000, current: 3, range: 1...9) == 4)
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#expect(snapped(5000, current: 8, range: 1...9) == 9)
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}
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// MARK: maxUnits — the boundary, not the ceiling
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@Test("maxUnits turns window headroom into whole growable units")
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func maxUnitsFromHeadroom() {
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// Two whole steps of headroom (2 × 112 = 224) → grow up to +2.
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#expect(LaneLayoutMath.maxUnits(currentUnits: 1, headroom: 250, step: step) == 3)
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// Just over one step → +1.
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#expect(LaneLayoutMath.maxUnits(currentUnits: 1, headroom: 120, step: step) == 2)
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// Less than a step → no window growth left, so the drag re-divides from its very first
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// tick; shrinking stays allowed either way.
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#expect(LaneLayoutMath.maxUnits(currentUnits: 1, headroom: 50, step: step) == 1)
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#expect(LaneLayoutMath.maxUnits(currentUnits: 2, headroom: 0, step: step) == 2)
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// Never below currentUnits even with a negative headroom (a window already past the visible
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// frame) — shrinking is always allowed.
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#expect(LaneLayoutMath.maxUnits(currentUnits: 2, headroom: -300, step: step) == 2)
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// No width ceiling to clamp against: a huge screen means a huge fit. The pathfinder capped
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// this at 3.
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#expect(LaneLayoutMath.maxUnits(currentUnits: 1, headroom: 10_000, step: step) == 90)
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// A degenerate step is not divided by.
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#expect(LaneLayoutMath.maxUnits(currentUnits: 2, headroom: 500, step: 0) == 2)
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}
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// MARK: Rubber-band resistance
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@Test("Inside the bounds the live width passes through untouched")
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func widthPassesThroughInsideBounds() {
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#expect(LaneLayoutMath.resistedWidth(proposed: 200, minSlot: slot(1),
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maxSlot: slot(3), resistance: 0.25) == 200)
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#expect(LaneLayoutMath.resistedWidth(proposed: slot(1), minSlot: slot(1),
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maxSlot: slot(3), resistance: 0.25) == slot(1))
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#expect(LaneLayoutMath.resistedWidth(proposed: slot(3), minSlot: slot(1),
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maxSlot: slot(3), resistance: 0.25) == slot(3))
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}
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@Test("Past either bound the edge gives only a quarter of the overshoot")
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func widthResistsPastEitherBound() {
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// 20 below the 100 floor → 100 − 20·0.25 = 95.
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#expect(LaneLayoutMath.resistedWidth(proposed: 80, minSlot: slot(1),
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maxSlot: slot(3), resistance: 0.25) == 95)
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// 76 above the 324 ceiling → 324 + 76·0.25 = 343.
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#expect(LaneLayoutMath.resistedWidth(proposed: 400, minSlot: slot(1),
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maxSlot: slot(3), resistance: 0.25) == 343)
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}
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}
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// MARK: - The drag past the screen
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/// The right-edge drag's **second regime** (03-board-ui.md § Lane, settled 2026-08-08): at the
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/// screen's visible frame the window stops growing, and each further tick re-divides the now-pinned
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/// strip across one more unit instead — the stepper's mechanism, driven by the drag, with the
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/// siblings compressing. Before this the tick simply clamped at the fit, so a lane on a maximised
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/// window refused to widen at all.
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///
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/// Fixture: the file's standard of 100 and gap of 12 on a **four-unit strip** — the dragged 1× lane,
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/// two more 1× lanes and the shown trash's fixed unit — with two whole steps of screen headroom, so
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/// the fit is 3×. The strip is 100·4 + 12·5 = 460 at drag start and 460 + 2·112 = 684 once the window
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/// is flush against the screen, which is the width every tick past 3× re-divides.
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@Suite("LaneLayoutMath ▸ the drag past the screen")
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struct LaneRedivideTests {
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private let startUnits = 1
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private let startTotal = 4
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private let fit = 3
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private let pinned: CGFloat = 684
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private func standardFor(_ units: Int) -> CGFloat {
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LaneLayoutMath.resizeStandard(
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forUnits: units, startUnits: startUnits, startStandard: standard,
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startTotalUnits: startTotal, fittingUnits: fit, gap: gap)
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}
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private func slotFor(_ units: Int) -> CGFloat {
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LaneLayoutMath.slotWidth(units: units, standard: standardFor(units), gap: gap)
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}
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private var ceiling: Int {
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LaneLayoutMath.resizeMaxUnits(
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startUnits: startUnits, startStandard: standard,
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startTotalUnits: startTotal, fittingUnits: fit, gap: gap)
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}
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private func snapped(_ liveWidth: CGFloat, current: Int) -> Int {
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LaneLayoutMath.snappedUnits(liveWidth: liveWidth, currentUnits: current,
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slotFor: slotFor, gap: gap,
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allowedRange: 1...ceiling, reentry: reentry)
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}
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// MARK: The pinned strip
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@Test("The pinned strip is the drag-start strip plus one step per unit of screen headroom")
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func pinnedStripWidthIsDerivedNotMeasured() {
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#expect(LaneLayoutMath.pinnedStripWidth(
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startUnits: startUnits, startStandard: standard,
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startTotalUnits: startTotal, fittingUnits: fit, gap: gap) == pinned)
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// No headroom at all: the strip is exactly what the frozen standard and the unit total
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// imply, and the re-divide starts from the very first tick.
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#expect(LaneLayoutMath.pinnedStripWidth(
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startUnits: startUnits, startStandard: standard,
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startTotalUnits: startTotal, fittingUnits: startUnits, gap: gap) == 460)
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}
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||
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||
// MARK: Continuity at the boundary
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@Test("The two regimes meet with no pixel jump")
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func theBoundaryCostsNothing() {
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// Everything up to the fit is the frozen standard: the window took the step, so the
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// division never moved.
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#expect(standardFor(1) == standard)
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#expect(standardFor(2) == standard)
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#expect(standardFor(fit) == standard, "the re-divided standard AT the fit is the frozen one")
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// Past it the same width divides across one more unit, so it can only shrink.
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#expect(standardFor(fit + 1) < standard)
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#expect(abs(standardFor(fit + 1) - 84) < 0.0001) // (684 − 12·8) / 7
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#expect(standardFor(fit + 2) < standardFor(fit + 1))
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||
}
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||
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@Test("Past the fit the strip still fills exactly — the width is pinned, the division is not")
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func exactFillSurvivesTheRedivide() {
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for units in (fit + 1)...12 {
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let redivided = standardFor(units)
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// Four boxes stand in the strip — the dragged lane, two 1× lanes and the trash — so
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// there are five gaps: the three between them and the two outer margins.
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let filled = slotFor(units) + 3 * redivided + 5 * gap
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#expect(abs(filled - pinned) < 0.0001, "\(units)× must still fill the pinned strip exactly")
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||
}
|
||
}
|
||
|
||
// MARK: The snap, measured slot by slot
|
||
|
||
@Test("A tick past the fit fires on the re-divided slot, and does not double-tick")
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||
func theRedivideTicksOnceAndSettles() {
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||
// 3× is the last slot the window pays for: 324 wide, its trailing gap ending at 336.
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||
let threshold = slotFor(fit) + gap
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||
#expect(threshold == 336)
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||
#expect(snapped(threshold, current: fit) == fit, "exactly at the far edge holds (strict >)")
|
||
|
||
let ticked = snapped(threshold + 0.1, current: fit)
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||
#expect(ticked == fit + 1, "the old clamp at the screen fit is gone")
|
||
|
||
// 4× is measured against the SMALLER standard the re-divide produced, and its threshold
|
||
// still sits beyond the width that fired the tick — so the session's iteration settles in
|
||
// one step rather than running away up the strip.
|
||
#expect(slotFor(fit + 1) + gap > threshold + 0.1)
|
||
#expect(snapped(threshold + 0.1, current: ticked) == ticked, "no double tick")
|
||
// And it does not immediately reverse either: the tick-down threshold is 10pt back inside
|
||
// the gap it just cleared.
|
||
#expect(snapped(threshold + 0.1, current: ticked) != fit)
|
||
}
|
||
|
||
@Test("Ticking back down retreats through the same re-divided slots")
|
||
func theRedivideTicksBackDown() {
|
||
// Coming back from 4×, the boundary is slot(3) + gap = 336 and the re-entry point 10pt
|
||
// inside it, at 326 — the same asymmetry as within the fit.
|
||
#expect(snapped(326, current: fit + 1) == fit + 1)
|
||
#expect(snapped(325.9, current: fit + 1) == fit)
|
||
#expect(snapped(330, current: fit + 1) == fit + 1, "re-entering the gap is not enough")
|
||
}
|
||
|
||
@Test("The ceiling is the strip's capacity, and units run well past the screen fit")
|
||
func theCeilingIsTheStripsCapacity() {
|
||
// 684 wide with 12pt gaps divides into at most 51 whole units before `standardWidth`'s 1pt
|
||
// floor would break the exact fill — floor((684 − 12) / 13) — and the dragged lane reads
|
||
// that back through the 47 units it added.
|
||
#expect(ceiling == 48)
|
||
#expect(ceiling >= fit)
|
||
#expect(standardFor(ceiling) >= 1)
|
||
#expect(abs(slotFor(ceiling) + 3 * standardFor(ceiling) + 5 * gap - pinned) < 0.0001)
|
||
// One unit further the 1pt floor engages, the division stops being a division, and the
|
||
// strip would overflow — which is precisely why the ceiling sits where it does.
|
||
#expect(standardFor(ceiling + 1) == 1)
|
||
#expect(slotFor(ceiling + 1) + 3 + 5 * gap > pinned)
|
||
// The snap walks all the way there and stops.
|
||
#expect(snapped(5000, current: fit) == fit + 1)
|
||
#expect(snapped(5000, current: ceiling) == ceiling)
|
||
}
|
||
|
||
@Test("The ceiling never falls below the screen fit, and a degenerate strip falls back to it")
|
||
func theCeilingFallsBackToTheFit() {
|
||
// Shrinking is always allowed, so the fit is the floor of the ceiling however odd the
|
||
// inputs are — a non-finite standard and a gap that would make the capacity formula
|
||
// meaningless both answer the fit rather than inventing a bound.
|
||
let degenerate: [(CGFloat, CGFloat)] = [(.nan, gap), (.infinity, gap), (standard, -1), (standard, -50)]
|
||
for (brokenStandard, brokenGap) in degenerate {
|
||
#expect(LaneLayoutMath.resizeMaxUnits(
|
||
startUnits: startUnits, startStandard: brokenStandard,
|
||
startTotalUnits: startTotal, fittingUnits: fit, gap: brokenGap) == fit)
|
||
}
|
||
// A start already past the fit (a window hanging off the screen) still cannot be clamped
|
||
// below where it stands.
|
||
#expect(LaneLayoutMath.resizeMaxUnits(
|
||
startUnits: 6, startStandard: .nan,
|
||
startTotalUnits: startTotal, fittingUnits: fit, gap: gap) == 6)
|
||
}
|
||
|
||
// MARK: The window's share of a tick
|
||
|
||
@Test("The window moves only for the part of a step that fits on screen")
|
||
func theWindowTakesOnlyItsShare() {
|
||
// Wholly inside the fit: every unit is the window's.
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 1, to: 3, fittingUnits: fit, step: step) == 2 * step)
|
||
// A flick across the boundary: only the first unit was ever the window's to give.
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 2, to: 5, fittingUnits: fit, step: step) == step)
|
||
// Wholly above it: the window is pinned and the re-divide does the whole of the work.
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 4, to: 7, fittingUnits: fit, step: step) == 0)
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: fit, to: fit + 1, fittingUnits: fit, step: step) == 0)
|
||
// Shrinking mirrors it exactly — the step handed back is the one that was taken.
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 5, to: 2, fittingUnits: fit, step: step) == -step)
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 7, to: 4, fittingUnits: fit, step: step) == 0)
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 3, to: 1, fittingUnits: fit, step: step) == -2 * step)
|
||
#expect(LaneLayoutMath.resizeWindowDelta(from: 4, to: 4, fittingUnits: fit, step: step) == 0)
|
||
}
|
||
}
|