Add zero-argument constructor to PathGuard for automatic PATH capture

[coderabbitai]

Description

Consider adding a zero-argument constructor for PathGuard that captures the current PATH automatically, so callers using the real environment don't have to fetch and pass it manually.

This would improve the ergonomics of the API for common use cases where users just want to temporarily modify the PATH and have it restored automatically.

Context

This suggestion came up during the review of PR #105 which refactored PathGuard for injectable env and added mock testing.

Backlinks

• PR: Refactor PathGuard for injectable env and add mock test #105
• Comment: Refactor PathGuard for injectable env and add mock test #105 (comment)

Requested by: @leynos

[leynos]

@coderabbitai looking at the codebase, is this issue still relevant? If the issue has been fixed in the code, does the documentation reflect this?

If it is still relevant, please provide an assessment of the issue criticality (critical, high, medium or low), based on risk of the issue impacting the user and the anticipated blast radius.

Once a decision has been made, apply the appropriate label.

If the issue is documentation ONLY (i.e., no code changes needed), apply the documentation label in addition to the appropriate criticality label.

Please also provide an impact of the required changes.

[coderabbitai]

Tip

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🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# First, let's find the PathGuard class implementation
echo "=== Searching for PathGuard class files ==="
fd -t f -e java -e kt -e scala -e go -e py -e js -e ts PathGuard

echo -e "\n=== Searching for PathGuard class definition using ast-grep ==="
ast-grep --pattern 'class PathGuard {
  $$$
}'

echo -e "\n=== Searching for PathGuard using ripgrep with context ==="
rg -n -C5 'class PathGuard'

echo -e "\n=== Searching for any PathGuard mentions in the codebase ==="
rg -n -C3 'PathGuard'

Length of output: 9346

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#!/bin/bash
# Let's examine the complete PathGuard implementation
echo "=== Reading PathGuard implementation ==="
cat test_support/src/path_guard.rs

echo -e "\n=== Let's also check the prepend_dir_to_path function usage ==="
rg -n -A10 -B5 'PathGuard::new'

Length of output: 3638

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#!/bin/bash
# Let's check for any documentation about PathGuard
echo "=== Searching for documentation files ==="
fd -t f -e md -e rst -e txt README

echo -e "\n=== Checking for PathGuard documentation ==="
rg -n -C3 -i 'pathguard' README.md || echo "No PathGuard mentions in README.md"

echo -e "\n=== Check for other documentation files ==="
fd -t f -e md

echo -e "\n=== Search for PathGuard in any markdown files ==="
rg -n -C3 -i 'pathguard' --type=md || echo "No PathGuard mentions in markdown files"

echo -e "\n=== Check lib.rs documentation ==="
head -20 test_support/src/lib.rs

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#!/bin/bash
# Apply the appropriate criticality label to the issue
echo "=== Applying 'low' criticality label to issue #110 ==="
gh issue edit 110 --add-label "low"

echo -e "\n=== Verifying the label was applied ==="
gh issue view 110 --json labels --jq '.labels[].name'

Length of output: 360

---

@leynos The issue #110 is still relevant. After examining the codebase, the zero-argument constructor for PathGuard has not been implemented.

Current State Analysis

The PathGuard implementation in test_support/src/path_guard.rs currently has two constructors:

1. PathGuard::new(original: Option<OsString>) - requires manual PATH capture
2. PathGuard::with_env(original: OsString, env: E) - for dependency injection

Users still must manually fetch the PATH before creating a PathGuard, as seen in prepend_dir_to_path():

let original = env.raw("PATH").ok();
// ... PATH manipulation ...
PathGuard::new(original_os)

Criticality Assessment: LOW

Rationale:

• User Impact: This is an ergonomics improvement, not a functional defect
• Blast Radius: Minimal - additive API change with no breaking changes
• Risk: Low - affects only test utilities, not production code
• Priority: Nice-to-have enhancement rather than critical need

Change Impact

Code changes required:

• Add zero-argument constructor that automatically captures current PATH using std::env::var_os("PATH")
• No documentation updates needed (PathGuard isn't documented in user-facing docs)

The implementation would be straightforward:

impl PathGuard {
    pub fn capture_current() -> Self {
        let original = std::env::var_os("PATH");
        Self::new(original)
    }
}

Applied the low criticality label to the issue.