Warn when config file exists but fails to parse

[simono]

Summary

Previously, prek install would silently fall back to default hook types when the config file existed but contained errors (e.g., invalid YAML or missing required fields). This made it hard to notice configuration mistakes.

Now it shows a warning with the specific error:

$ prek install
warning: Failed to parse `.pre-commit-config.yaml`: Invalid remote repo: missing field `rev`
prek installed at `.git/hooks/pre-commit`

Test plan

• Added install_invalid_config_warning test
• All existing install tests pass

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR adds warnings when prek install encounters a configuration file that exists but fails to parse, preventing silent fallback to default behavior that could mask configuration errors.

Changes:

• Warning message now displays the specific parse error when config file is invalid
• Fallback to default hook types still occurs, but users are notified
• Test coverage added for invalid config warning behavior

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
crates/prek/tests/install.rs	Adds integration test verifying warning appears for invalid config
crates/prek/src/cli/install.rs	Implements warning logic for config parse errors in two code paths

[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: +0.00% (22.5 MiB → 22.5 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text    Size           Crate Name
 0.3%   0.8% 71.7KiB           prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.3%   0.6% 59.5KiB            prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.6% 56.1KiB            prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5% 43.4KiB            prek prek::identify::by_extension::{{closure}}
 0.2%   0.5% 43.2KiB            prek prek::run::{{closure}}
 0.2%   0.4% 41.7KiB            prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4% 40.8KiB            prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.1%   0.3% 31.2KiB           prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2% 21.6KiB            prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 21.6KiB            prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 21.0KiB    clap_builder clap_builder::parser::parser::Parser::get_matches_with
 0.1%   0.2% 20.8KiB            prek prek::archive::unzip::{{closure}}
 0.1%   0.2% 20.0KiB cargo_metadata? <cargo_metadata::_::<impl serde_core::de::Deserialize for cargo_metadata::Package>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2% 19.5KiB            prek prek::cli::run::filter::collect_files_from_args::{{closure}}
 0.1%   0.2% 19.3KiB            prek <prek::languages::ruby::ruby::Ruby as prek::languages::LanguageImpl>::install::{{closure}}
 0.1%   0.2% 19.1KiB            prek prek::cli::run::filter::collect_files_from_args::{{closure}}
 0.1%   0.2% 18.6KiB            ring ring_core_0_17_14__x25519_ge_frombytes_vartime
 0.1%   0.2% 18.5KiB            prek prek::hook::HookBuilder::build::{{closure}}
 0.1%   0.2% 18.5KiB            prek prek::hook::HookBuilder::build::{{closure}}
 0.1%   0.2% 18.5KiB            prek prek::hook::HookBuilder::build::{{closure}}
36.8%  91.6%  8.3MiB                 And 20028 smaller methods. Use -n N to show more.
40.2% 100.0%  9.1MiB                 .text section size, the file size is 22.5MiB

Base Branch Results

 File  .text    Size           Crate Name
 0.3%   0.8% 71.7KiB           prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.3%   0.6% 59.2KiB            prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.6% 55.6KiB            prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5% 43.4KiB            prek prek::identify::by_extension::{{closure}}
 0.2%   0.5% 43.3KiB            prek prek::run::{{closure}}
 0.2%   0.5% 42.4KiB            prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.4% 41.7KiB            prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3% 31.8KiB           prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2% 21.6KiB            prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 21.0KiB    clap_builder clap_builder::parser::parser::Parser::get_matches_with
 0.1%   0.2% 20.8KiB            prek prek::archive::unzip::{{closure}}
 0.1%   0.2% 20.0KiB cargo_metadata? <cargo_metadata::_::<impl serde_core::de::Deserialize for cargo_metadata::Package>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2% 19.8KiB            prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 19.4KiB            prek prek::cli::run::filter::collect_files_from_args::{{closure}}
 0.1%   0.2% 19.4KiB            prek prek::cli::run::filter::collect_files_from_args::{{closure}}
 0.1%   0.2% 19.3KiB            prek <prek::languages::ruby::ruby::Ruby as prek::languages::LanguageImpl>::install::{{closure}}
 0.1%   0.2% 18.6KiB            ring ring_core_0_17_14__x25519_ge_frombytes_vartime
 0.1%   0.2% 18.5KiB            prek prek::hook::HookBuilder::build::{{closure}}
 0.1%   0.2% 18.5KiB            prek prek::hook::HookBuilder::build::{{closure}}
 0.1%   0.2% 18.5KiB            prek prek::hook::HookBuilder::build::{{closure}}
36.9%  91.6%  8.3MiB                 And 20035 smaller methods. Use -n N to show more.
40.2% 100.0%  9.1MiB                 .text section size, the file size is 22.5MiB

[codecov]

Codecov Report

❌ Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 91.51%. Comparing base (a69f9eb) to head (6cf4f10).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/config.rs	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1487      +/-   ##
==========================================
+ Coverage   91.35%   91.51%   +0.15%     
==========================================
  Files          87       87              
  Lines       18187    18167      -20     
==========================================
+ Hits        16615    16625      +10     
+ Misses       1572     1542      -30     

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[j178]

Thanks!