One-line reference for every Biloba method and matcher, grouped by area — selectors/locators, lifecycle, poll-config (WithTimeout/WithPolling/WithContext/Immediate), capturing a matcher's observed value (.Capture), navigation (GetLocation/GetTitle), cookies/storage, tabs, DOM existence/visibility/contents/properties/forms, clicking and interactions (incl. drag/scroll/tap/modifiers/text-selection), realistic mode, keyboard, uploads, element JS, dialogs, downloads, arbitrary JS (incl. the GetJSValue app-state barrier), network stubbing/aborting/modifying/observing/holding (HoldResponse + Limit/ReleaseNext), screenshots/outline/window, and visual regression (HaveScreenshot + Mask/Tolerance/ChannelTolerance/Animated/InColorSchemes). Use to look up the exact method or matcher name and shape. Methods marked (dual) poll until they succeed when fully applied and return a pollable matcher when under-applied.
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name
api
description
One-line reference for every Biloba method and matcher, grouped by area — selectors/locators, lifecycle, poll-config (WithTimeout/WithPolling/WithContext/Immediate), capturing a matcher's observed value (.Capture), navigation (GetLocation/GetTitle), cookies/storage, tabs, DOM existence/visibility/contents/properties/forms, clicking and interactions (incl. drag/scroll/tap/modifiers/text-selection), realistic mode, keyboard, uploads, element JS, dialogs, downloads, arbitrary JS (incl. the GetJSValue app-state barrier), network stubbing/aborting/modifying/observing/holding (HoldResponse + Limit/ReleaseNext), screenshots/outline/window, and visual regression (HaveScreenshot + Mask/Tolerance/ChannelTolerance/Animated/InColorSchemes). Use to look up the exact method or matcher name and shape. Methods marked (dual) poll until they succeed when fully applied and return a pollable matcher when under-applied.
Naming conventions — assume these, they're only restated where an entry breaks them:
Shape
Means
Have* / Be* / Each* / Match*
a Gomega matcher. Each* = ≥1 match AND all satisfy (fails on zero matches).
Get*
polls the first match until ready, returns the value. Optional trailing &ptr decodes it.
Current*ForEach
snapshot over all matches, no poll, returns a slice (empty when nothing matches).
*Immediately
acts on all current matches now, no poll. The long suffix is a "know what you're doing" smell.
(dual)
fully applied → polls, acts once, stops (b.Click("#go")). Under-applied → a matcher you poll (Eventually("#go").Should(b.Click())).
Selectors: CSS strings, XPath (biloba:xpath), or Locators. b.Immediate() opts out of poll-by-default; rarely needed.
Selectors / locators
CSS is the default (stable #id/[data-testid], not styling classes); locators for a11y + text/label identifiers; XPath the rare axis/ordinal tool. Speed: CSS > XPath > locators (full-document ARIA scan).
CSS: "#id", .cls, :has(). >>> pierces one open-shadow-root / same-origin-iframe boundary per occurrence.
XPath: b.XPath(...) — pierces neither.
Locators (*Contains variant on every text-valued one): b.ByRole(r), b.ByText, b.ByLabel, b.ByPlaceholder, b.ByAltText, b.ByTitle, b.ByTestID(id) (attr = biloba.TestIDAttribute, default "data-testid"), b.ByCSS(sel) — raw CSS into the algebra, the only structural constructor (b.ByCSS(".story").Nth(1) for "the 2nd", not :nth-of-type). They pierce open shadow roots automatically. Accessible name covers aria-labelledby/aria-label/<label>/alt/placeholder/value/text/figcaption/caption/title.
Role refinements: .WithName(n)/.WithNameContains(n), .Level(n), .Checked()/.Disabled()/.Expanded()/.Pressed()/.Selected().
Composition (each accepts any CSS/XPath/Locator): .ContainingText/.NotContainingText, .Containing/.NotContaining, .And/.Or, .Within/.NotWithin, .Nth(i)/.First()/.Last(). E.g. b.ByRole("listitem").Containing(b.ByText("Delete")).Within("#cart").First().
Trap — an unresolved scope matches nothing, so a negative assertion is vacuous. Anchor the scope first:
Configuring anything that resolves to a bare matcher — a (matcher) method (b.HaveScreenshot(name), b.Exist(), …), or the under-applied dual form (b.WithTimeout(d).Click()) — is also a hard error. Configure the Eventually, not the matcher.
.Capture(&target)
Every matcher that reads a value off the page returns a *ValueMatcher with .Capture(&x): it writes what it observed on a successful match, so the gate and the read are one read (asserting then re-reading with a getter is two reads of a page that may have changed — TOCTOU).
var blockID string
Eventually(".figure-frame").Should(b.HaveAttribute("data-block-id", Not(BeEmpty())).Capture(&blockID))
Typed decode: any non-nil pointer, decoded à la encoding/json — a JS number lands in an *int as 3, not float64(3); a JS object lands in your struct. An impossible mismatch (string into *int) fails immediately instead of waiting out the timeout.
Absent vs. zero: a JS null/undefined decodes to the Go zero value, so a plain *string target can't tell "absent" apart from "present but empty." Decode into a **T instead — absent leaves it nil, present allocates: var key *string; b.GetAttribute(".mark", b.AllowMissing("data-key"), &key). Re-evaluated on every observation, so a poll watching an absent→present transition stays honest. Matters most under AllowMissing (below), whose whole point is making absence a value rather than a timeout.
Only on a match:ShouldNot/NotTo captures nothing. While polling the target is overwritten each successful attempt; it holds the value from the attempt that passed.
Returns a NEW matcher, leaves the receiver alone — m.Capture(&idA) then m.Capture(&idB) is safe. HaveCookie's .Capture copies too and composes with .With* in either order.
Narrowing works for JS objects, not Biloba structs. A struct naming a subset of a JS object's fields is fine (HaveJSONAttribute). Box/ScrollOffset/BoxDelta/Cookie into a different struct is rejected rather than half-filled — capture into the matching type or an any.
Capturable:HaveAttribute, HaveProperty (both forms incl. existence-only), HaveValue, HaveInnerText, HaveTextContent, HaveText, HaveClass, HaveCount, HaveDistinctCount, HaveJSONAttribute, HaveComputedStyle, HaveComputedStyleNumeric, EachHaveInnerText, , , (both forms — the existence-only form reads values in the same round-trip, so no-arg / capture too), , , /, , , , , /, /, , .
b.GetLocation() / b.GetTitle() → string — polling getters, all four knobs. A transient CDP error mid-navigation (Inspected target navigated or closed (-32000)) is a retryable miss. (Breaking rename — bare Location/Title are gone.)
b.HaveURL(string|matcher) / b.HaveTitle(string|matcher) — same transient-error behavior.
Gate on a DOM anchor, not the URL — Eventually("#dashboard-root").Should(b.Exist()) proves the navigation landed; a GetLocation() read is then a formality.
Cookies & storage (navigate to a real origin first)
b.SetCookie(...Cookie) (default domain = current URL) · b.GetCookies() → Cookies · b.ClearCookies().
b.Count(selector) → int (snapshot) · b.HaveCount(int|matcher).
b.HaveDistinctCount(attribute, int|matcher) — count of distinct values attribute takes across matches (dedupes double-painted nodes by a stable data-* key).
b.BeVisible() — non-zero offsetWidth/offsetHeight. · b.BeEnabled() — !el.disabled. · b.BeClickable() — visible + enabled + topmost at its center (deterministic occlusion guard; Click does not run it). · b.EachBeVisible() / b.EachBeEnabled().
Every Each* matcher means "≥1 match AND all satisfy" — it fails on zero matches instead of passing vacuously. Assert nothing matches with HaveCount(0) / ShouldNot(b.Exist()).
Contents, classes, attributes, state
b.GetInnerText(selector) → string (polls on presence — "" is a valid value) · b.HaveInnerText(string|matcher) (exact).
b.CurrentInnerTextForEach(selector) → []string · b.EachHaveInnerText(value|matcher). Same pair for CurrentTextContentForEach/EachHaveTextContent. The no-argEachHaveInnerText()/EachHaveTextContent() no longer mean "every text is empty" — they assert the property is defined on every match and capture the slice. Sub-matcher and .Capture both see a typed []string (the same slice the Current*ForEach getter returns), so Equal([]string{...}) and HaveExactElements(...) both work — contrast the generic EachHaveProperty below, which hands over raw []any.
b.HaveClass(string|matcher) — a string ⇒ "list contains"; a matcher receives []string. · b.EachHaveClass(string).
b.HaveAttribute(name[, string|matcher]) — via getAttribute.
b.HaveComputedStyle(prop, string|matcher) — via getComputedStyle; getter b.GetComputedStyle (see Geometry).
b.BeChecked(). An element with no checked property at all is an error, not "unchecked" — selecting the wrapping <label>/<div> fails loudly instead of letting ShouldNot(b.BeChecked()) pass forever.
b.BeFocused() — is document.activeElement.
Properties (. paths like dataset.name; JS types preserved — numbers are float64)
Two-axis polling: the singular Get* getters poll until the element is present AND every named property/attribute is defined.
Trap: a property that doesn't exist on that element type (disabled on a <div>) blocks the poll to timeout. Wrap it — b.GetProperty("div.card", b.AllowMissing("disabled")) → nil, no wait. Name params take string or AllowMissing; AllowMissing applies to GetProperty/GetProperties/GetAttribute/GetAttributes only.
b.GetAttribute(selector, name[, &ptr]) → any (raw getAttribute markup, not the resolved property) · b.GetAttributes(selector, ...names) → Properties.
b.GetJSONAttribute(selector, attribute, &out) (polls until present, set, and JSON-parseable, then decodes into *struct/*map/*any) · b.HaveJSONAttribute(attribute, matcher) — hands the sub-matcher the decoded value (map[string]any/[]any/float64); composes with gstruct.
Snapshot plural getters — no poll, nil for absent, gate presence first with Eventually(sel).Should(b.HaveCount(n)):b.CurrentPropertyForEach(selector, name[, &ptr]) → []any · b.CurrentPropertiesForEach(selector, ...names) → SliceOfProperties (.Get(key), .Find(key, val|matcher), .Filter(key, val|matcher)) · b.CurrentAttributeForEach · b.CurrentAttributesForEach.
Trap: they return an empty slice when nothing matches, which satisfies a negated collection assertion (Ω(b.CurrentInnerTextForEach(".row")).ShouldNot(ContainElement("Draft")) passes against zero rows). The gate keeps the negative honest. Positive assertions are safer — Gomega's errors on an empty slice.
Form values (rationalizes text/checkbox/radio/multi-select)
b.GetValue(selector[, &ptr]) → any (polls on presence only — ""/unselected radio is a valid value; bool for checkbox, checked radio's value, []string for multi-select) · b.CurrentValueForEach(selector[, &ptr]) → []any.
b.SetValue(selector, value) (dual) — requires visible+enabled; focuses, sets, fires input+change. Does not type real keys (use b.Type). For a <select> the value matches the option value, not its visible label.
b.ValueLabel(label) — wrap a SetValue arg to target a <select> option by visible label: b.SetValue(sel, b.ValueLabel("Sonnet")). Multi-select: pass a slice (labels and raw values may mix). <select> only.
b.HaveValue(value|matcher).
Geometry (pollable layout reads — use instead of hand-rolled b.Run geometry)
Getters poll until the element is present AND laid out (non-degenerate box). All values are viewport-relative CSS pixels. Each getter has a Have* matcher counterpart.
A missing element is an error, not a non-match. So Eventually("#toast").ShouldNot(b.BeInViewport())times out — Gomega never counts an erroring matcher as satisfied, in either direction. Assert disappearance with ShouldNot(b.Exist()) or Should(b.HaveCount(0)); keep geometry matchers for elements that are there. Applies to HaveBoundingBox/HaveScrollOffset/HaveOffsetTopWithin/HaveOffsetLeftWithin/HaveGapBetween, the pairwise matchers, and any Consistently(sel).ShouldNot(...) on a conditionally-rendered sel. Under Eventually an error is still just a failed attempt, and a present-but-zero-area box is a silent retry, so positive assertions poll through late layout. (Matches BeVisible/BeEnabled/BeClickable, which always errored on a missing element. The pairwise/offset probes name which selector went missing: subject, container, or other.)
b.GetBoundingBox(selector) → Box{Top,Left,Width,Height,Bottom,Right,CenterX,CenterY,ClientWidth,ClientHeight} · b.HaveBoundingBox(matcher) (receives the Box; compose with HaveField). Width/Height are border-box (incl. scrollbar gutter, like getBoundingClientRect); ClientWidth/ClientHeight are the client box (content+padding, scrollbar excluded) — "content width of this scroll container".
b.GetScrollOffset(selector) → ScrollOffset{Top,Left,MaxTop,MaxLeft} (Top==MaxTop ⇒ scrolled to bottom) · b.HaveScrollOffset(matcher).
Pairwise (both boxes read in one atomic frame — don't split into two GetBoundingBoxes): b.BeAbove(other) (subject.Bottom<=other.Top), b.BeBelow, b.BeLeftOf (subject.Right<=other.Left), b.BeRightOf, b.Encloses (all 4 edges), b.Overlaps. All matchers: Eventually(subject).Should(b.BeAbove(other)).
b.GetGapBetween(selector, other) → BoxDelta{Top,Left,Bottom,Right,Width,Height,CenterX,CenterY} (subject minus other; CenterX~0 ⇒ shared center line, Width~0 ⇒ same size) · b.HaveGapBetween(other, value|matcher).
b.BeInViewport(options...) — laid out and intersecting the visible layout viewport (≠ BeVisible, which is only "rendered"). Partial overlap counts; b.Fully() requires all 4 edges on screen.
b.BePrecededBy(other) / b.BeFollowedBy(other) — document order via compareDocumentPosition. Read the subject first:Should(b.BeFollowedBy(Y)) ⇔ X comes Y; ⇔ X comes Y. A backwards assertion doesn't flake — it silently passes on a fixture satisfying the inverse, so pin both sides (). Failure messages report the observed order (). "Anywhere after" includes — scope with .
Clicking & interactions (pragmatic simulations)
b.Click(selector) (dual) — visible+enabled, then el.click().
Pointer options — b.At(x,y) (offset from top-left; canvas/map/slider) and b.Shift()/b.Ctrl()/b.Alt()/b.Meta() (⌘/Win) — accepted by Click/DblClick/RightClick/MiddleClick/Tap, after the selector or in place of it (matcher form). They compose: b.Click(sel, b.At(30,40), b.Shift()). In fast mode any option switches the click off native el.click() to a synthetic event carrying coords+flags.
b.DragTo(source, target) (dual) — pointer-based drag (pointerdown/move/up); drives @dnd-kit-style DnD, not native HTML5 draggable. Matcher subject is the source.
b.ScrollWheel(selector, deltaX, deltaY) (dual; matcher form drops the selector) — wheel event then scrolls the nearest scrollable ancestor; +deltaY=down, +deltaX=right.
b.ClickEachImmediately(selector) — click all visible+enabled matches now, no poll (gate presence first).
b.ScrollIntoView(selector, ...ScrollOption) (dual) — bare = native scrollIntoView(). Options: b.WithinScroller(container) (a specific container, not the nearest ancestor), (land below the container top — "clear the sticky header"). Instant, occlusion-aware.
Selecting text
Each produces a genuine window.getSelection() range and dispatches mouseup (drives highlight→menu/annotation UIs).
b.SelectText(selector) (dual) — all of the element's text.
b.SelectText(selector, substring[, b.Occurrence(n)]) (dual) — a substring; first occurrence by default, b.Occurrence(n) is 1-based. The matcher form requires an explicit b.Occurrence(n) so it can't be confused with select-all: Eventually("#passage").Should(b.SelectText("fox", b.Occurrence(2))).
b.SelectRange(selector, start, end) (dual; matcher form drops the selector) — chars [start, end) across the element's text nodes; fails the spec if out of bounds.
b.ClearSelection() — no matcher form.
Read back with Eventually("window.getSelection().toString()").Should(b.EvaluateTo(…)).
Realistic mode → biloba:realistic-mode
b.Realistic() → *Biloba — a view of the same tab routed through real CDP input: scrolls into view, waits for stability, refuses to click through an occluding overlay, moves the real pointer (CSS :hover activates), dispatches genuine mouse/touch/key input. The whole interaction vocabulary works on it; it composes with the poll-config clones (b.Realistic().WithTimeout(d).Click(sel)). No per-call decorator. Per-spec opt-in — real round-trips, can reintroduce flake.
Keyboard (real key events, via chromedp)
b.Type(...) (dual) — the element-targeted keyboard method: focuses (which scrolls into view), then genuine keystrokes (text and named Keys.*); appends. Arg disambiguation (after stripping modifiers):
b.Type(payload) — matcher form: a single string, or one-or-more Keys.*. Eventually("#in").Should(b.Type(biloba.Keys.Enter)).
The matcher form can't mix leading text + trailing keys (b.Type("hello", Keys.Enter) reads as selector="hello"). Use the polling form.
b.SendKeysToWindowImmediately(...parts) — focus-free, no selector, no matcher, no poll: lands on the focused element, else fires on document/window (global hotkeys). Gate it yourself: Eventually(sel).Should(b.BeFocused()) then send. To type into an element use b.Type.
Modifiersb.Shift()/b.Ctrl()/b.Alt()/b.Meta() (same values as the pointer modifiers) work here too, in any position: b.Type("textarea", biloba.Keys.Enter, b.Shift()).
Uploads
b.SetUpload(selector, ...paths) (dual) — set <input type=file> files via CDP (paths must exist on Chrome's machine); fires change. Matcher form: b.SetUpload(path) or, for multiple files, a single b.SetUpload([]string{...}) (bare variadic paths would be ambiguous with the immediate form).
b.Dialogs() → Dialogs, filtered with .OfType(biloba.DialogTypeAlert|DialogTypeConfirm|DialogTypePrompt|DialogTypeBeforeunload), .MatchingMessage(string|matcher), .MostRecent(). There is no dialog matcher — assert with plain Gomega: Ω(b.Dialogs().MostRecent()).Should(HaveField("Message", "…")).
Dialog{Type, Message, DefaultPrompt, HandleResponse, HandleText, Autohandled} (Autohandled = no registered handler matched, so a Biloba default ran).
Arbitrary JS (runs on the global window; wrap object literals in parens)
b.Run(script[, &ptr]) → any — a synchronous expression; returns the decoded value. A top-level return is illegal (errors with a hint pointing at RunAsync/IIFE). Pollable: Eventually(b.Run).WithArguments(expr).Should(matcher) — it's a func(string,...any) any. → biloba:flaky-specs
b.RunAsync(script[, &ptr]) — the body of an async fn; you return the awaited value (use for await/fetch).
b.RunErr(script, ...args) / b.RunErrAsync(...) → (any, error) — error-returning siblings; handle the error yourself instead of failing the spec.
b.EvaluateTo(value|matcher) — assert a JS expression's result. Numbers decode to float64 — BeNumerically, not Equal(intLiteral). Asymmetry: the sub-matcher sees the raw JSON-decoded value ([]any of map[string]any — HaveKeyWithValue, not HaveField); .Capture(&typed) hands you the value decoded into your struct.
b.JSFunc(script) → .Invoke(...args) string — JSON-encodes args into an invocable snippet. · b.JSVar(nameOrExpr) — reference a JS variable/expression as a JSFunc argument (don't quote it).
b.GetJSValue(expression[, &ptr]) → any — polls until expression is defined, then returns it. The app-state barrier: point it at a global the app writes (window.__storeLog) to prove the browser processed something. Retries through undefinedand a thrown error (a ReferenceError for a not-yet-created global is "not ready"); null is a legitimate value and returns immediately. The pointer decodes into a concrete type (dodges the float64 gotcha).
It gates on definedness and nothing else — it only barriers on a path created lazily by the event you're waiting for (window.__log ??= [] inside the subscriber). Against an -created log it returns on the first tick and gates nothing.
Network (per-tab; reset by Prepare)
b.StubRequest(url string|matcher, biloba.StubResponse{Status,Body,Headers}) — the first handler enables interception; unmatched requests pass through.
b.AbortRequest(url string|matcher) — fail matching requests (the page's fetch rejects).
b.ModifyRequest(url string|matcher) → .WithURL(u).WithMethod(m).WithHeader(n,v).WithBody(b) — continue to the real network, overriding only what you set.
b.ModifyResponse(url string|matcher) → .WithStatus(s).WithHeader(n,v).WithBody(b) or .Using(func(biloba.InterceptedResponse) biloba.StubResponse) — rewrite the real response (reads real status/headers/body; heavier — pauses twice).
Every registration returns a handle whose Count() reports how many dispatches that handler claimed — *RequestStub/*RequestAbort/*RequestModification/*ResponseModification (plus *ResponseHold below). A snapshot, safe to poll: Eventually(stub.Count).Should(Equal(1)). Assert your handler fired — a typo'd URL otherwise matches nothing, goes straight to the real network, and the spec passes for the wrong reason. Count is a fact about that handler, not the URL: first-match-wins means a handler shadowed by an earlier one stays at 0.
All handlers share one ordered, first-match-wins list. In an Ordered container Prepare() is OncePerOrdered, so handlers accumulate across the Its: an earlier spec's handler permanently claims that URL and a later identical one is silent dead code. → biloba:flaky-specs §6
While interception is on Biloba disables the HTTP cache (Network.setCacheDisabled(true), restored by Prepare()) — a cached response raises no Fetch event and would skip every handler.
Intercepts the real response and holds it in flight until you release it (then it passes through unchanged). Builds on ModifyResponse — same tab scoping, same first-match-wins list. The tool for forcing arrival order in optimistic-UI reconciliation → biloba:flaky-specs.
A hold freezes EVERY matching response by default, not just the first. That's right for "nothing lands until I say so"; use Limit for "hold #1 while #2 flies past".
hold.Await() → InterceptedResponse — blocks until a match is actually held, then returns the oldest one still held (immediately if one already arrived). Responses that passed through at Limit were never held, so Await skips them; after a bare Release() it returns the first response the hold intercepted rather than blocking. Waiting command: own 30s default, honors WithTimeout/WithContext set on the tab you build the hold from (b.WithTimeout(d).HoldResponse(u)); WithPolling/Immediate are a hard error.
hold.Limit(n) → *ResponseHold — hold at most n concurrently; while n are held, further matches pass straight through untouched (they still count). Releasing frees capacity. n ≥ 1; unlimited by default. The limit is consulted only as each response arrives — set it when you build the hold (lowering it later releases nothing; raising it retro-holds nothing).
hold.Release() — terminal: everything held goes through AND the hold stops holding future matches. Idempotent.
hold.Release(r) — release just the response Await() gave you; the hold stays armed. Releasing something this hold isn't holding fails the spec (matched by value, oldest first).
hold.ReleaseNext() — release the oldest still-held response and stay armed (Await(); ReleaseNext(); Await() steps through them). Fails the spec when nothing is held.
hold.Count() → int — every match intercepted so far, held or passed through. A snapshot (no knobs) but safe to poll: Eventually(hold.Count).Should(Equal(1)). Assert it — it's the only proof the interception you think happened actually did.
hold.Held() / hold.PassedThrough() → int — split Count(): Held is how many this hold actually froze (cumulative, including ones since released); is how many arrived and were never frozen (at , or after a bare ). always; both snapshots, safe to poll. With the fixture under test is usually "response #2 was NOT held" — assert directly rather than , which only implies it by inference from the limit (a regression that raises the limit keeps green while destroying the ordering under test).
b.CaptureScreenshotOf(selector) · b.CaptureImgcatScreenshotOf(selector) · b.CaptureScreenshotOfToFile(selector, path) — clipped to the first match (any selector; works below the fold and across >>>).
b.SetWindowSize(w, h, ...opt) · b.WindowSize(). SetWindowSize registers its own DeferCleanup to restore the prior size — don't restore manually, and don't call it from inside another DeferCleanup (Ginkgo forbids nesting). Call it bare in BeforeEach/BeforeAll.
Visual regression → biloba:visual-assertions
b.HaveScreenshot(name string, ...ScreenshotOption) — bare matcher; compares the subject against the committed baseline <name>.png. Subject is a selector (element capture, clipped to its box) or the tab b (whole page). Every poll attempt captures and compares afresh, so the poll waits out fonts/ResizeObserver/rAF. name may contain / for subdirectories. Configure the Eventually (a knob on the matcher is a hard error); Gomega's 1s default is usually too short.
Options (ScreenshotOption): b.Mask(selectors...) paints matches flat gray on both sides of the comparison (no-op if nothing matches) · b.Tolerance(fraction) at most fraction (0..1) of pixels may differ · b.ChannelTolerance(delta) a pixel only counts as differing when an R/G/B/A channel is off by more than delta (the antialiasing absorber) · b.Animated() opts out of the automatic animation/transition/caret/smooth-scroll freeze (which reaches open shadow roots, not closed ones) · b.InColorSchemes(schemes...) compares once per emulated prefers-color-scheme, all must match, baseline per scheme <name>-<scheme>.png. Both tolerances default to 0 (exact).
Baselines are committed (./biloba-baselines, BilobaConfigScreenshotBaselinesDir / BILOBA_SCREENSHOT_BASELINES_DIR); the .actual.png/.diff.png a failure writes are gitignored, landing in the failure-screenshots dir. Suite-wide tolerance: BilobaConfigScreenshotTolerance(fraction) / BilobaConfigScreenshotChannelTolerance(delta).
A missing baseline fails (never write-and-pass) and says to re-run with BILOBA_UPDATE_SCREENSHOTS=1, which writes baselines and reports in words what changed. Update mode captures until three in a row match before writing (so a write takes ~0.5–2.2s) and warns if the page never settles. The var takes ; an unrecognised value warns. A failed comparison prints a text diagnosis (pixel counts, the changed-region shape, the untouched side) plus the three paths.
EachHaveTextContent
EachHaveClass
EachHaveProperty
EachHaveInnerText()
EachHaveTextContent()
HaveBoundingBox
HaveScrollOffset
HaveOffsetTopWithin
HaveOffsetLeftWithin
HaveGapBetween
EvaluateTo
HaveURL
HaveTitle
HaveLocalStorageItem
HaveSessionStorageItem
HaveNumLocalStorageItems
HaveNumSessionStorageItems
HaveNumCookies
HaveCookie
Not capturable (won't compile): value-less matchers — Exist, BeVisible, BeEnabled, BeClickable, BeFocused, BeChecked, BeInViewport, BeAbove/BeBelow/BeLeftOf/BeRightOf/Encloses/Overlaps/BePrecededBy/BeFollowedBy, BeNetworkIdle, HaveScreenshot — and the actions-as-matchers (Click, SetValue, Type, …). Two read something but stay bare on purpose: MatchColor (a sub-matcher — capture off the HaveComputedStyle you hand it to) and HaveMadeRequest (a *RequestQuery builder; it renders observed requests in its failure message, and the request object comes from b.AllRequests().Find(b.RequestMatching(...))).
Getter counterpart: the any-returning getters take an optional trailing pointer with the same decode rules — b.GetProperty("#row", "offsetWidth", &n), b.GetAttribute, b.GetValue, b.CurrentPropertyForEach, b.CurrentAttributeForEach, b.CurrentValueForEach. The value is still returned.
HaveCount(n)
HaveEach
b.SetPropertyForEachImmediately(selector, name, value) — all matches now, no poll. · b.EachHaveProperty(name[, ...]) — sub-matcher and .Capture see the raw JSON-decoded []any (properties are heterogeneous, nothing honest to convert to); Equal([]string{...}) always fails here — use HaveExactElements(...).
BEFORE
Should(b.BePrecededBy(Y))
AFTER
Ω(X).ShouldNot(b.BePrecededBy(Y))
Actually: #note comes BEFORE #section.
inside
Locator.NotWithin
b.GetComputedStyle(selector, property) → string (getPropertyValue, so kebab-case names and custom properties like --stage resolve).
b.GetComputedStyleNumeric(selector, property) → float64 (leading number via parseFloat: "16px"→16; non-numeric fails) · b.HaveComputedStyleNumeric(property, number|matcher) — a plain number compares with BeNumerically.
b.NormalizeColor(color) → string (pure transform: no selector, no poll) — any CSS <color> incl. a var(--token) chain (resolved against :root) → canonical rgb()/rgba(). · b.MatchColor(color) — normalizes both sides; pass as the expected: b.HaveComputedStyle("stroke", b.MatchColor("var(--tok-teal)")).
b.AtTopOffset(px)
px
un
Fast clicks act in place — no scrollIntoView, no focus move. Scroll-into-view comes only from Realistic() and from focus-bearing ops (Focus/SetValue/Type).
eagerly
[]
Wrong wherever absence is meaningful (a ledger absent on about:blank means quiet; window.__renderErrors absent means no errors; a flag that must have survived; a pre-action baseline). Those stay b.Run with a coalesce (window.__x ?? null).
For a condition rather than a value: Eventually(expr).Should(b.EvaluateTo(matcher).Capture(&typed)). → biloba:flaky-specs §3
b.BeNetworkIdle() — zero in-flight requests at the instant it's polled, no quiet period. Tracks HTTP only (Network.requestWillBeSent/loadingFinished); a long-lived WebSocket does not keep it busy. It passes before your request has started — anchor with Eventually(b).Should(b.HaveMadeRequest(...)) first, then wait for idle.
PassedThrough
Limit
Release()
Held()+PassedThrough()==Count()
Limit(1)
Eventually(hold.PassedThrough).Should(Equal(1))
Count()==2
Count
Count/Release are facts about the network, not the page — Count says a response reached the tab's interceptor, Release returns when the release is signalled; neither says the renderer did anything with it. When the assertion is about what the app did with the response, pair them with an app-state barrier (b.GetJSValue, or the DOM the response produces), not a sleep.
Held responses are force-released at spec end and by Prepare().
Sharp edge: matching is tab-wide and URL-based, so a hold can catch a response from an earlier page load. Scope to a dedicated b.NewTab(), or assert Count(). A second HoldResponse for a URL an earlier one already claims is dead code — re-arm the hold you have with ReleaseNext.
