testing library

A graphics backend that draws nothing and remembers everything.

The counterpart to the fake texture source in frame_resources_test.dart, and it exists for the same reason. Every type a pass used to name — gpu.RenderPass, gpu.HostBuffer, gpu.Shader, gpu.RenderPipeline — needed a live device to construct, so nothing that encoded anything could be tested at all. What a node draws was checked by looking at a golden image twelve minutes later, or not at all.

With the backend arriving as a value, a node can be handed one of these and asked what it did: which passes it opened, what they were attached to, what state it left them in, what it bound and how many times it drew.

Why it is in lib/, and in this package

It was four hundred and seventy-five lines in two copies, and they had already drifted. flutter3d/test/fake_backend.dart and flutter3d_particles/test/fake_backend.dart were the same file down to the paragraph above — which still names a test that only exists in one of them — and the particles copy was twenty-six lines behind: no pendingFrames, no completesImmediately, no uploadedPixels. A test written against it could not ask the question those exist to answer, and nothing said so.

This package rather than a new one, because that is what it depends on: flutter3d_hardware and flutter/widgets, and nothing else. A separate flutter3d_fakes would be a twenty-second workspace entry holding one file.

In lib/ rather than in a shared test/, because a package cannot import another package's test/ — which is the reason there were two copies.

import 'package:flutter3d_hardware/testing.dart';

Recorded and its subclasses — one entry per thing a pass was told to do — are src/testing_recorded.dart. FakePass, the CommandEncoder that records them, is src/testing_fake_pass.dart. FakeShaderLibrary and FakeBackend, the GraphicsDevice that opens one, are src/testing_fake_backend.dart. All three are re-exported from here.

So is SynchronousBufferReadback, since 1.0: the read that stalls the caller until the GPU is done is a test's or a tool's, never a frame's, so the main library does not offer it. A backend that has it imports it from here to mix it in.

And MaskedDevice, since 1.0.0-rc.1: any live device, answering as if it lacked the features a test names, so the fallback branch of each runs on the machine at hand.

Classes

FakeBackend

A device that records rather than draws.

FakeComputePass

A compute pass that records rather than runs: each call a RecordedCall in commands, in order, after the checks a real encoder makes (the storage range and its alignment, the dispatch size).

FakeCubeTarget

One cube render target a FakeBackend was asked for, as FakeBackend.createdCubeRenderTargets lists it.

FakeGeometryOverwrite

One overwrite of a geometry buffer a FakeBackend recorded, as FakeBackend.overwrites lists it: wiring, not content.

FakeLoadedShaderLibrary

What FakeBackend.loadShaders hands back: the bundle's own names, answered with handles that survive a reload.

FakeMapping

A mapping of bytes a fake never had: zeros, handed back on unmap.

FakePass

A pass that was opened, and everything that went into it.

FakeReadback

One readback a FakeBackend was asked for, as FakeBackend.readbacks lists it.

FakeShaderLibrary

A bundle that has every stage anybody asks for, except the ones it is told to withhold.

FakeTextureOverwrite

One overwrite of a texture a FakeBackend recorded, as FakeBackend.overwrittenTextures lists it: wiring, not content.

FakeTransfer

A transfer pass that records its copies into the device's calls, and refuses those the device's features lack.

MaskedDevice

inner, answering as if it lacked MaskedDevice.disabledFeatures.

Recorded

One thing recorded into a pass, in order.

RecordedAlphaToCoverage

PassEncoder.setAlphaToCoverage, in sequence; see RecordedPrimitiveType.

RecordedBlend

PassEncoder.setBlend, for one colour attachment.

RecordedBlendColor

PassEncoder.setBlendColor.

RecordedCall

A 1.0-surface call — a storage bind, a query, an indirect or bundled draw, a buffer write, a copy — recorded by name with its arguments.

RecordedClearBindings

PassEncoder.clearBindings.

RecordedCullMode

PassEncoder.setCullMode, in sequence; see RecordedPrimitiveType.

RecordedDepthCompare

PassEncoder.setDepthCompare, in sequence; see RecordedPrimitiveType.

RecordedDepthWrite

PassEncoder.setDepthWrite, in sequence; see RecordedPrimitiveType.

RecordedDraw

PassEncoder.draw, with the instance count and index window it asked for.

RecordedIndices

PassEncoder.bindIndexBuffer or bindIndexData: the width and count, not which buffer.

RecordedPipeline

PassEncoder.bindPipeline.

RecordedPolygonMode

PassEncoder.setPolygonMode, in sequence; see RecordedPrimitiveType.

RecordedPrimitiveType

Rasteriser state, recorded in sequence as well as kept as a field.

RecordedScissor

PassEncoder.setScissor.

RecordedStencil

A stencil configuration, with the back face only when one was named.

RecordedStencilReference

PassEncoder.setStencilReference, in sequence; see RecordedPrimitiveType.

RecordedTexture

PassEncoder.bindTexture.

RecordedUniformBlock

PassEncoder.bindUniformBlock.

RecordedVertices

PassEncoder.bindVertexBuffer or bindVertexData: how many vertices, not which buffer.

RecordedViewport

PassEncoder.setViewport.

RecordedWindingOrder

PassEncoder.setWindingOrder, in sequence; see RecordedPrimitiveType.

Mixins

SynchronousBufferReadback

A device that reads a buffer back in the calling turn — DeviceFeature.synchronousReadback.

Functions

computePlacementOf(ComputeSite site) → ComputePlacement

Where site is, for a test checking the rule — exported from package:flutter3d_hardware/testing.dart only.