python-dotenv 1.2.2: Pin python-dotenv string parsing: escape sequences expand only in double quotes, and inline comments require preceding whitespace only when unquoted.

# python-dotenv String Parsing & Inline Comments

## 1. Search Result
A search for known solutions using `search_known_solution` returned a sample (`sha256:6032931e56a20b51b652c9f7c77e9a8fb979e1513bcd63e107668998f1f1f80f`) covering return semantics, `dotenv_values` isolation, and interpolation precedence. This sample covers a completely different behavior: string literal parsing, escape sequences, and inline comments.

## 2. What a Model Would Have Written Instead
A model would confidently expect that single quotes process escape sequences identically to double quotes (expanding `\n` to a newline). It would also assume that `#` consistently starts an inline comment, either always requiring a preceding space, or never requiring it, regardless of whether the preceding value is quoted.

## 3. How the Wrong Version Fails
If a model writes `VAR='\n'` expecting a newline, it fails silently with a green build because the application receives a literal backslash followed by an 'n' instead of a newline. Similarly, if a model expects `VAR=val#3` to strip `#3` as a comment (as it does in bash after a space), it fails because the `#` is parsed as part of the literal string. Conversely, assuming `VAR="val"#3` includes `#3` as part of the string (since it lacks a space) fails because `#` directly following a closing quote is always parsed as a comment.

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python-dotenv==1.2.2

import io
import dotenv

def test_parsing_rules():
    env_content = (
        "VAR_UNQUOTED=\\n\n"
        "VAR_SINGLE='\\n'\n"
        "VAR_DOUBLE=\"\\n\"\n"
        "VAR_UNQUOTED_HASH=val#3\n"
        "VAR_UNQUOTED_SPACE_HASH=val #3\n"
        "VAR_QUOTED_HASH=\"val\"#3\n"
    )
    parsed = dotenv.dotenv_values(stream=io.StringIO(env_content))

    # Escape sequence parsing
    assert parsed.get("VAR_UNQUOTED") == "\\n", "assert unquoted \\n is literal backslash-n"
    assert parsed.get("VAR_SINGLE") == "\\n", "assert single-quoted \\n is literal backslash-n"
    assert parsed.get("VAR_DOUBLE") == "\n", "assert double-quoted \\n is actual newline"

    # Inline comment parsing
    assert parsed.get("VAR_UNQUOTED_HASH") == "val#3", "assert unquoted # without preceding space is part of the string"
    assert parsed.get("VAR_UNQUOTED_SPACE_HASH") == "val", "assert unquoted # with preceding space is a comment"
    assert parsed.get("VAR_QUOTED_HASH") == "val", "assert # immediately following a closing quote is a comment"

if __name__ == "__main__":
    test_parsing_rules()
    print("CONTRACT PASS: python-dotenv escape sequences and comments verified")

import io
import dotenv

env_content = """
# Unquoted escape sequences
VAR1=\\n
# Single quoted escape sequences
VAR2='\\n'
# Double quoted escape sequences
VAR3="\\n"

# Export prefix
export VAR4=val4

# Inline comments
VAR5=val5 # This is a comment
VAR6="val6 # This is NOT a comment"

# Spaces around equals
VAR7 = val7
"""

parsed = dotenv.dotenv_values(stream=io.StringIO(env_content))
for k, v in parsed.items():
    print(f"{k}: {repr(v)}")