Skip unused work in discovery post-processing and output#2918
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The WriteScreen plugin flattened the whole discovered tree with View-Flat on DiscoveryEnd, but the result is only read when Run.SkipRun is set or verbosity is Detailed/Diagnostic, in the default run it was computed and thrown away. It is now computed only when one of those consumers can read it. The RSpec decoration walk (Add-RSpecTestObjectProperties per test) and Remove-RSpecNonPublicProperties used Fold-Container/Fold-Run, which pay a scriptblock dispatch per item and an advanced-function recursion per block. Both are now direct recursive loops that visit the same items in the same pre-order. Format-Nicely2 called Is-DecimalNumber, Is-ScriptBlock, Is-Collection and Is-Value helpers on every formatted value, on the dispatch path used for every <template> name expansion. The type checks are inlined, the helpers stay defined for other callers. 🤖
This was referenced Jul 19, 2026
fflaten
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Jul 19, 2026
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Just curious so I can learn, what's the big benefit here besides clearer names? We skip maybe 1-2 light function calls, but all the scriptblocks are reference types and passed on from the initial call.
| if (Is-DecimalNumber -Value $Value) { | ||
| # Inlined Is-DecimalNumber / Is-ScriptBlock to avoid a function call per formatted value on this | ||
| # hot dispatch path (used for every <template> name expansion). The helpers stay defined for other callers. | ||
| if ($Value -is [float] -or $Value -is [single] -or $Value -is [double] -or $Value -is [decimal]) { |
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Is-DecimalNumber is only used here and Format.ps1. Maybe update both?
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Three changes on the discovery and post-processing side:
View-FlatonDiscoveryEnd, but the result is only read whenRun.SkipRunis set or verbosity isDetailed/Diagnostic. In the default run it was computed and thrown away, the cost grows with the number of discovered tests. It is now computed only when one of those two guarded blocks can actually read it.Add-RSpecTestObjectPropertiesper test, run once per container after it finishes) andRemove-RSpecNonPublicPropertiesusedFold-Container/Fold-Run, which pay a scriptblock dispatch per item plus an advanced-function recursion per block. Both are now direct recursive loops that visit the same items in the same pre-order (tests of a block before its child blocks). The decoration body itself is unchanged and stays in one place, the walker just calls it.Format-Nicely2called theIs-DecimalNumber,Is-ScriptBlock,Is-CollectionandIs-Valuehelpers on every formatted value, and it runs for every<template>name expansion of data-driven tests. The type checks are inlined (Is-Collectionis the sameLanguagePrimitives::GetEnumeratortest), the helpers stay defined for their other callers.Verification: full suite green on macOS (inline and dot-sourced build),
Pester.RSpec.ts.ps1,Pester.RSpec.Parallel.ts.ps1(covers the parallel decoration path, which changed too) andPester.RSpec.Output.ts.ps1pass in fresh processes. Result object shape is covered byPester.RSpec.ResultObject.ts.ps1, also green.Related perf PRs: #2914, #2915, #2916, #2917. Measured together they cut ~21% from four representative workloads (inline build, macOS).
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