Fix formatter adding extra space at end of line without trailing newline

[Copilot]

Problem

The formatter was incorrectly adding a space at the end of files that don't have a trailing newline. For example, formatting a file containing just 1; (with no trailing newline) would result in 1; (with a space added after the semicolon).

Root Cause

The EndOfFileToken was incorrectly included in the allTokens array, which caused the "SpaceAfterSemicolon" formatting rule to match between semicolon and EOF tokens. TypeScript explicitly excludes EOF from its allTokens array to prevent this.

Solution

internal/format/rules.go: Modified getAllRules() to exclude ast.KindEndOfFile when building the allTokens array, matching TypeScript's behavior.

internal/format/format_test.go: Added comprehensive test cases to verify the fix works for various code patterns including simple statements, function calls, variable declarations, and multiple statements without trailing newlines.

Testing

All tests pass, including:

• New test cases specifically for files without trailing newlines
• Existing format tests continue to pass
• Language service integration tests pass
• Code passes linter and formatter checks

The fix is minimal and focused - it only changes the token rules to exclude EOF from allTokens, preventing the "SpaceAfterSemicolon" rule from incorrectly applying between semicolon and EOF tokens.

Fixes #1926

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Formatter adds extra space at end of line</issue_title>
<issue_description>Format a a file that has this content (no trailing new line):

1;

Bug
An extra space is added at the end of the line</issue_description>

<agent_instructions>Create and commit a failing test FIRST. Then compare against the original formatter in _submodules/TypeScript/src/services/formatting/formatting.ts.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@jakebailey An extra space, or an extra newline? @mjbvz Seems like an extra space in this case:

Trace - 11:40:37 AM] Sending notification 'textDocument/didChange'.
Params: {
    "textDocument": {
        "uri": "file:///Users/matb/projects/sandbox/x.ts",
        "version": 130
    },
    "contentChanges": [
        {
            "range": {
                "start": {
                    "line": 0,
                    "character": 2
                },
                "end": {
                    "line": 0,
                    "character": 2
                }
            },
            "rangeLength": 0,
            "text": " "
        }
    ]
}
```</body></comment_new>
</comments>

Fixes #1926

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[iisaduan]

This probably fixes the extra newlines that @andrewbranch found when working on autoimports formatting?

[jakebailey]

This is correct, reading Strada.

[Copilot]

Pull Request Overview

This PR fixes a bug where the formatter incorrectly added a trailing space to files without a trailing newline. The root cause was that EndOfFileToken was being included in the allTokens array, causing the "SpaceAfterSemicolon" formatting rule to trigger between semicolons and EOF.

Key changes:

• Excluded ast.KindEndOfFile from the allTokens array in the rule builder
• Added comprehensive test coverage for formatting files without trailing newlines

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
internal/format/rules.go	Modified token array building to exclude EOF token, preventing incorrect spacing rules
internal/format/format_test.go	Added new test file with test cases verifying no trailing spaces are added to files without trailing newlines