02 / DIFFERENTIAL

GovsNode

Test URL	Observed difference
`http:evil.com`	Node → host=`evil.com`, path=`/`; Go → host=`''`, path=`evil.com` (opaque URL)
`http:\\evil.com\hello`	Node → normalizes `\` to `/`, host=`evil.com`, path=`/hello`; Go → opaque URL with backslashes in path
`http:/evil.com`	Node → host=`evil.com`, path=`/`; Go → host=`''`, path=`/evil.com`
`http://example．com/`	Node → host=`example.com` (NFKC-normalizes fullwidth dot); Go → host=`example．com` (raw)
`http://exmp.com/#hello\n\rSet-Cookie: evil`	Node → strips raw CR/LF, percent-encodes spaces in fragment; Go → keeps CR/LF and spaces raw in fragment
`http://exmp.com/?hello=\n\rSet-Cookie: evil`	Node → strips raw CR/LF, percent-encodes spaces in query; Go → keeps CR/LF and spaces raw in query
`file://localhost/c:/hello`	Node → host=`''`, path=`c:/hello` (drops the particular hostname for `localhost` when path starts with `[a-zA-Z]:/`); Go → host=`localhost`, path=`/c:/hello`
`file:hello//etc/passwd`	Node → host=`''`, path=`hello//etc/passwd`; Go → host=`''`, opaque URL (not treated as host+path)
`http://127.1`	Node → host=`127.0.0.1` (normalizes integer IPs); Go → host=`127.1` (raw)
`http://2130706433/a`	Node → host=`127.0.0.1`; Go → host=`2130706433` (raw)
`http://0x7f000001/a`	Node → `127.0.0.1`; Go → `0x7f000001` (raw)
`http://0177.0.0.1/a`	Node → `127.0.0.1`; Go → `0177.0.0.1` (raw)
`http://017700000001/a`	Node → `127.0.0.1`; Go → `017700000001` (raw)
`http://1234567890/a`	Node → `73.150.2.210` (decimal→IP); Go → `1234567890` (unchanged)
`http://bücher.com/`	Node → host=`xn--bcher-kva.com` (Punycode); Go → host=`bücher.com` (raw)
`https://exmp.com/hello/../world`	Node → path=`/world` (normalizes dot-segments); Go → path=`/hello/../world` (raw)

02 / DIFFERENTIAL

RustvsNode

Test URL	Observed difference
`file://example.com/c:/hello`	Rust → host=`''`, path=`c:/hello` (drops any hostname when path starts with Windows drive segment*; Node → host=`example.com`, path=`/c:/hello` (only drops `localhost`)
`file://example.com//hello`	Rust → host=`example.com`, path=`/hello` (normalizes multiple leading slashes); Node → host=`example.com`, path=`//hello` (no normalization)
`file://example.com/c:/../hello`	Rust → path=`/c:/hello` (normalizes `..` until first Windows drive segment*); Node → path=`/hello` (removes all `..` segments)

02 / DIFFERENTIAL

RustvsGo

Test URL	Observed difference
`http:\\example.com\hello`	Rust → normalizes `\` to `/`, host=`example.com`, path=`/hello`; Go → opaque URL with backslashes kept in Opaque
`http:/example.com/hello/`	Rust → host=`example.com`, path=`/hello/` (segment after `http:/` is the hostname); Go → host=`''`, path=`/example.com/hello/`
`http:example.com/hello/`	Rust → host=`example.com`, path=`/hello/`; Go → host=`''`, opaque URL `example.com/hello/`
`file:etc/passwd`	Rust → path=`/etc/passwd`; Go → opaque URL `etc/passwd`
`custom:hello`	Rust → path=`hello`; Go → opaque URL `hello`
`http://127.1`	Rust → host=`127.0.0.1` (normalizes integer IPs); Go → host=`127.1` (raw)
`http://2130706433/a`	Rust → host=`127.0.0.1`; Go → host=`2130706433` (raw)
`http://0x7f000001/a`	Rust → host=`127.0.0.1`; Go → host=`0x7f000001` (raw)
`http://0177.0.0.1/a`	Rust → host=`127.0.0.1`; Go → host=`0177.0.0.1` (raw)
`http://017700000001/a`	Rust → host=`127.0.0.1`; Go → host=`017700000001` (raw)
`http://1234567890/a`	Rust → host=`73.150.2.210` (decimal→IP); Go → host=`1234567890` (raw)
`http://example.com/path?query bar`	Rust → percent-encodes query (`query%20bar`); Go → keeps raw (`query bar`)
`http://example.com/path#frag bar`	Rust → percent-encodes fragment (`frag%20bar`); Go → keeps raw (`frag bar`)
`http://example.com/hello/../there`	Rust → path=`/there` (normalizes dot-segments); Go → path=`/hello/../there` (raw)
`file://example.com/c:/hello`	Rust → host=`''`, path=`/c:/hello` (drops any hostname when path starts with `[a-zA-Z]:/`); Go → host=`example.com`, path=`/c:/hello`
`http://example.com/#hello\n\rSet-Cookie:evil`	Rust → drops raw CR/LF, fragment=`helloSet-Cookie:evil`; Go → keeps CR/LF raw in fragment
`http://example.com/?hello=1\n\rSet-Cookie:evil`	Rust → drops raw CR/LF, query=`hello=1Set-Cookie:evil`; Go → keeps CR/LF raw in query
`https://bücher.example/`	Rust → host=`xn--bcher-kva.example` (IDNA Punycode); Go → host=`bücher.example` (raw)
`http://www．example．com/`	Rust → host=`www.example.com` (normalizes fullwidth dot); Go → host=`www．example．com` (raw)

02 / DIFFERENTIAL

RustvsPython

Test URL	Observed difference
`http:\\example.com\hello`	Rust → normalizes `\` to `/` and uses it as a delimiter, host=`example.com`, path=`/hello`; Python → treats `\` as part of the path, host=`''`, path=`\example.com\hello`
`http:/example.com/hello/`	Rust → host=`example.com`, path=`/hello/`; Python → host=`''`, path=`/example.com/hello/`
`http:example.com/hello/`	Rust → host=`example.com`, path=`/hello/`; Python → host=`''`, path=`example.com/hello/`
`http:///user@host`	Rust → treats the segment after `///` as userinfo/host (user=`user`, host=`host`); Python → host=`''`, path=`/user@host`
`http://127.1`	Rust → host=`127.0.0.1`; Python → host=`127.1` (raw)
`http://2130706433/a`	Rust → host=`127.0.0.1`; Python → host=`2130706433` (raw)
`http://0x7f000001/a`	Rust → `127.0.0.1`; Python → `0x7f000001` (raw)
`http://0177.0.0.1/a`	Rust → `127.0.0.1`; Python → `0177.0.0.1` (raw)
`http://017700000001/a`	Rust → `127.0.0.1`; Python → `017700000001` (raw)
`http://1234567890/a`	Rust → `73.150.2.210` (decimal→IP); Python → `1234567890` (unchanged)
`http://example.com/path?query bar`	Rust → percent-encodes query (`query%20bar`); Python → keeps raw (`query bar`)
`http://example.com/path#frag bar`	Rust → percent-encodes fragment (`frag%20bar`); Python → keeps raw (`frag bar`)
`http://example.com/hello/../there`	Rust → path=`/there` (normalizes dot segments through one level of URL encoding, up to the first Windows drive segment*); Python → path=`/hello/../there` (raw)
`file://example.com/c:/hello`	Rust → host=`''`, path=`/c:/hello` (drops hostname when path starts with `[a-zA-Z]:/`); Python → host=`example.com`, path=`/c:/hello`
`https://bücher.example/`	Rust → host=`xn--bcher-kva.example` (IDNA Punycode); Python → host=`bücher.example` (raw)
`http://www．example．com/`	Rust → host=`www.example.com` (normalizes fullwidth characters); Python → host=`www．example．com` (raw)

02 / DIFFERENTIAL

NodevsPython

Test URL	Observed difference
`http:/example.com/hello`	Node → host=`example.com`, path=`/hello`; Python → host=`''`, path=`/example.com/hello` (matches Go's behavior)
`http:///example`	Node → host=`example`, path=`/`; Python → host=`''`, path=`/example`
`http:evil.com` (no slash at all)	Node → host=`evil.com`, path=`/`; Python → host=`''`, path=`evil.com`
`http:evil.com//extra`	Node host=`evil.com` path=`//extra`; Python host=`''` path=`evil.com//extra`
`http://ex\ample.com/a`	Node ends host at `\`: host=`ex`, path=`/ample.com/a`; Python keeps `\` in the host: host=`ex\\ample.com`
`http://exa．mple.com/a`	Node NFKC-normalizes host to `exa.mple.com`; Python keeps the raw fullwidth dot in host
`http://example.com/hello/../world`	Node normalizes path to `/world`; Python keeps `/hello/../world`
`http://example.com/.%2e/`	Node normalizes (`%2e` recognized as `..`) → path=`/`; Python keeps `/.%2e/` unchanged
`http://example.com/./a/./b/./c`	Node → `/a/b/c`; Python → `/./a/./b/./c`
`file://localhost/etc/passwd`	Node drops host → `''`; Python keeps host=`localhost` (Go also keeps it)
`http://bücher.example/café?q=✓#résumé`	Node Punycode-encodes the host (`xn--bcher-kva.example`) and percent-encodes non-ASCII characters in path, query, and fragment; Python keeps everything raw
`http://127.1/a`	Node converts to IPv4 `127.0.0.1`; Python keeps host=`127.1`
`http://2130706433/a`	Node → host=`127.0.0.1`; Python → host=`2130706433` (raw)
`http://0x7f000001/a`	Node → `127.0.0.1`; Python → `0x7f000001` (raw)
`http://0177.0.0.1/a`	Node → `127.0.0.1`; Python → `0177.0.0.1` (raw)
`http://017700000001/a`	Node → `127.0.0.1`; Python → `017700000001` (raw)
`http://1234567890/a`	Node → `73.150.2.210`; Python → `1234567890` (unchanged)
`http://example.com/path#frag bar`	Python fragment = `frag bar`; Node = `frag%20bar`
`http://example.com/path?query bar`	Python query = `query bar`; Node = `query%20bar`
`http://example.com/a#frag\\r\\nSet-Cookie: evil`	Both strip raw CR/LF silently; Python also keeps the trailing space raw, Node encodes it (`fragSet-Cookie: evil` vs `fragSet-Cookie:%20evil` in fragment)

02 / DIFFERENTIAL

PythonvsGo

Test URL	Observed difference
`http:example/hello`	Go → `example/hello` is opaque; Python → `example/hello` is the path.
`http://exmp.com/#hello\n\rSet-Cookie: evil`	Python → strips raw CR/LF, keeps spaces in fragment; Go → keeps CR/LF and spaces raw in fragment
`http://exmp.com/?hello=\n\rSet-Cookie: evil`	Python → strips raw CR/LF, keeps spaces in query; Go → keeps CR/LF and spaces raw in query
`http://EXAMPL%E.COM`	Go host → `EXAMPLE.COM`; Python host → `exampl%E.COM` (lowercases up to the first `%` character).
`http://example.com/hello%2Fworld\there`	Go path → `hello/world%5Cthere` (URL-decodes once and encodes unsafe characters); Python path → `hello%2Fworld\there` (unchanged).
`http://user:p%40ss.example.com`	Go password → `p@ss` (URL-decodes it); Python password → `p%40ss` (unchanged).