Exclude directories, not just files, in ExcludePath

[nohwnd]

Fix #1575

Problem

Run.ExcludePath is documented as "Directories or files to be excluded from the run.", but directory exclusions were silently ignored — only file paths and wildcard patterns actually excluded anything.

The cause is in Filter-Excluded (src/Pester.RSpec.ps1): each discovered test file's full path was only tested against every exclusion with -like. When the exclusion is a directory (e.g. C:\proj\excluded), no file inside that directory matches, because -like needs an exact/glob match against the whole file path. So Invoke-Pester -Path <root> -ExcludePath <root>\excluded still ran the tests under excluded.

Fix

Keep the existing wildcard/exact -like behavior, and additionally treat a non-wildcard exclusion as a directory prefix: a file is excluded when its normalized full path starts with the exclusion plus a directory separator.

• Trailing separators are trimmed, so dir and dir\ behave the same.
• The prefix comparison is case-insensitive on Windows and case-sensitive on Linux/macOS (matching the filesystem).
• Wildcard exclusions (e.g. */excluded/*) are left entirely to -like, so existing glob behavior is unchanged.

Tests

Added a regression block in tst/Pester.RSpec.ts.ps1 (Excluding directories from a run) with a two-subdirectory layout, asserting that:

• excluding a directory removes the tests underneath it while a sibling directory still runs, and
• the same works when the excluded path has a trailing separator.

Both fail on main and pass with this change. The rest of Pester.RSpec.ts.ps1 is unaffected (the 3 remaining failures in that file are pre-existing and unrelated — SkipRemainingOnFailureCount). PSScriptAnalyzer with the repo settings reports no new findings on the changed lines.

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com