Add GitHub Action to check trailing whitespace on PRs

[Copilot]

Adds automated trailing whitespace detection for pull requests to maintain code consistency.

Implementation

• Workflow: .github/workflows/trailing-whitespace-check.yml
  • Triggers on PR open/sync/reopen events
  • Scans only changed files (not entire codebase)
  • Covers text files: .cs, .csproj, .sln, .ts, .html, .css, .scss
  • Excludes: build artifacts (bin/, obj/, artifacts/), dependencies (node_modules/, packages/), hidden dirs, IDE files
  • Reports line numbers with trailing whitespace
  • Fails check if issues found

Security

• Minimal permissions: contents: read
• Passes CodeQL analysis

Example Output

❌ Trailing whitespace found in: src/Example.cs
42:         return value;  
55:     }  

❌ Found trailing whitespace in 1 file(s).

Original prompt

Please create a GitHub Action which checks new code for trailing whitespace on PRs

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[softworkz]

@copilot

Please add a few changes in files which create trailing whitespace

[Copilot]

@copilot

Please add a few changes in files which create trailing whitespace

Added two demo files with trailing whitespace in commit 6f4e1f0:

• src/ElectronNET.CLI/TrailingWhitespaceDemo.cs (C# file with trailing spaces)
• src/ElectronNET.WebApp/test-trailing-whitespace.html (HTML file with trailing spaces)

These files will trigger the workflow check on this PR, demonstrating how it detects trailing whitespace.

[softworkz]

@copilot - Great! Now remove the extra files so that we can merge

[Copilot]

@copilot - Great! Now remove the extra files so that we can merge

Removed the demo files in commit 5d5bda0. The PR now only contains the workflow file and is ready for merge.

[Copilot]

Pull Request Overview

This PR adds automated trailing whitespace detection for pull requests to maintain code consistency. The workflow checks only changed files against trailing whitespace issues and reports specific line numbers where issues are found.

Key Changes:

• Implements a GitHub Actions workflow that triggers on PR events (open, sync, reopen)
• Checks text files (.cs, .csproj, .sln, .ts, .html, .css, .scss) for trailing whitespace
• Excludes build artifacts and dependencies from checks
• Provides detailed output with line numbers and fails the check if issues are found

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[Copilot]

The head -10 command limits the display to 10 lines but doesn't affect the count in line 64. This means if there are exactly 10 lines with trailing whitespace, line 64 will calculate (10 - 10) = 0 and display "... and 0 more lines", which is confusing.

Consider changing the condition to check if the count is greater than 10:

if [ $(grep -c '[[:space:]]$' "$file") -gt 10 ]; then
  EXTRA=$(($(grep -c '[[:space:]]$' "$file") - 10))
  echo "   ... and $EXTRA more lines"
fi

Or simplify by checking if EXTRA is greater than 0.

Suggested change

	if [ $(grep -c '[[:space:]]$' "$file") -gt 10 ]; then
	echo " ... and $(($(grep -c '[[:space:]]$' "$file") - 10)) more lines"
	EXTRA=$(($(grep -c '[[:space:]]$' "$file") - 10))
	if [ "$EXTRA" -gt 0 ]; then
	echo " ... and $EXTRA more lines"

[Copilot]

The grep command on line 64 is executed multiple times within the same if block, which is inefficient. Consider storing the count in a variable first:

TRAILING_COUNT=$(grep -c '[[:space:]]$' "$file")
echo "❌ Trailing whitespace found in: $file"
grep -n '[[:space:]]$' "$file" | head -10
if [ "$TRAILING_COUNT" -gt 10 ]; then
  echo "   ... and $(($TRAILING_COUNT - 10)) more lines"
fi

This avoids running grep multiple times on the same file.

Suggested change

	echo "❌ Trailing whitespace found in: $file"
	grep -n '[[:space:]]$' "$file" | head -10
	if [ $(grep -c '[[:space:]]$' "$file") -gt 10 ]; then
	echo " ... and $(($(grep -c '[[:space:]]$' "$file") - 10)) more lines"
	TRAILING_COUNT=$(grep -c '[[:space:]]$' "$file")
	echo "❌ Trailing whitespace found in: $file"
	grep -n '[[:space:]]$' "$file" | head -10
	if [ "$TRAILING_COUNT" -gt 10 ]; then
	echo " ... and $(($TRAILING_COUNT - 10)) more lines"