wanderbooks/crates/ledger-config/src/lib.rs

//! Company settings as an older books dir's `wanderbooks.toml` holds them.
//!
//! Nothing that serves or shows books reads that file (D-44): the books
//! keep their own settings in their journal. The file is read once, when
//! `wanderbooks books adopt` brings an older books dir in whole (`codec`
//! moves its settings, and its `config.json`'s receipt policy, into the
//! journal), and `books.export_settings` writes the books' settings out as
//! one. It holds the company name (report headers), the fiscal year start
//! (fiscal-year-to-date reports), the members of a multi-member LLC
//! (`[[company.members]]`: name, share, capital account — for the
//! statement of members' equity), `[books] accounting_basis` (report
//! footers), and `[books] receipt_threshold` (the receipt policy, unless
//! the books dir's `config.json` sets one). The fiscal year *end* is never
//! stored: it is the day before the next start, so the two can't disagree.

pub mod codec;
pub mod receipt_policy;
pub use ledger_core::settings::{Company, Member, PartyPolicy, decimal};
pub use receipt_policy::ReceiptPolicy;

use rust_decimal::Decimal;
use serde::Deserialize;

/// What a `wanderbooks.toml` says, read (`parse`); and the books' own
/// settings in the same shape (`codec::books_settings`).
#[derive(Clone, Debug, Default, PartialEq)]
pub struct BooksSettings {
    /// `[company]`.
    pub company: Company,
    /// `[books] receipt_threshold`, validated as a decimal string.
    pub receipt_threshold: Option<String>,
    /// `[books] receipt_required_accounts`: account codes whose entries
    /// always need a receipt (unless `config.json` sets a policy).
    pub receipt_required_accounts: Vec<String>,
    /// `[books] receipt_exempt_accounts`: account codes exempt from the
    /// receipt rule (unless `config.json` sets a policy).
    pub receipt_exempt_accounts: Vec<String>,
    /// `[books] cash_accounts`: account codes that hold cash (bank,
    /// savings, cash on hand), for cash reports and dashboards. Empty:
    /// callers decide (e.g. by account name).
    pub cash_accounts: Vec<String>,
    /// `[books] financing_accounts`: liability account codes the cash flow
    /// statement treats as financing (loans, and what owners advanced:
    /// ASC 230-10-45-14(b)); equity is financing unlisted. Empty: other
    /// liabilities are operating (the statement never guesses from names).
    pub financing_accounts: Vec<String>,
    /// `[books] investing_accounts`: asset account codes the cash flow
    /// statement treats as investing (loans the company makes, investments
    /// it buys: ASC 230-10-20). Registered fixed assets need not be listed.
    pub investing_accounts: Vec<String>,
    /// `[books] asset_tag_prefix`: the prefix of generated asset tags
    /// ("FL" for "FL-0001"). Unset: [`BooksSettings::asset_tag_prefix`]
    /// derives it from the company name.
    pub asset_tag_prefix: Option<String>,
    /// `[books] parties`: how hard the agent asks for each entry's
    /// counterparty. Unset: [`PartyPolicy::Suggest`].
    pub parties: PartyPolicy,
    /// `[company] timezone`: the company's time zone (an IANA name), what
    /// "today" means for the books. Unset: the computer's.
    pub timezone: Option<String>,
}

impl BooksSettings {
    /// The prefix generated asset tags use: `[books] asset_tag_prefix`, or
    /// else the initials of the company name's words, legal-form words
    /// (LLC, Inc, Corp, ...) left out, at most 8 ("Fernhill Labs LLC" →
    /// "FL"); "FA" (fixed asset) when the name gives none.
    pub fn asset_tag_prefix(&self) -> String {
        if let Some(p) = &self.asset_tag_prefix {
            return p.clone();
        }
        const FORMS: &[&str] = &[
            "llc",
            "l",
            "c",
            "inc",
            "incorporated",
            "corp",
            "corporation",
            "co",
            "company",
            "ltd",
            "limited",
            "llp",
            "lp",
            "pllc",
            "pc",
            "pa",
            "the",
            "and",
            "of",
        ];
        let initials: String = self
            .company
            .name
            .split(|c: char| !c.is_ascii_alphanumeric())
            .filter(|w| !w.is_empty() && !FORMS.contains(&w.to_ascii_lowercase().as_str()))
            .filter_map(|w| w.chars().next())
            .filter(char::is_ascii_alphabetic)
            .map(|c| c.to_ascii_uppercase())
            .take(8)
            .collect();
        if initials.is_empty() || self.company.name == Company::default().name {
            "FA".to_string()
        } else {
            initials
        }
    }
}

#[derive(Deserialize)]
struct BooksToml {
    #[serde(default)]
    company: CompanyToml,
    #[serde(default)]
    books: BooksSection,
    #[serde(default)]
    vault: VaultSection,
}

#[derive(Default, Deserialize)]
struct VaultSection {
    key_file: Option<String>,
}

#[derive(Default, Deserialize)]
struct CompanyToml {
    name: Option<String>,
    fiscal_year_start: Option<String>,
    tax_form: Option<String>,
    tax_classification: Option<String>,
    timezone: Option<String>,
    #[serde(default)]
    members: Vec<MemberToml>,
}

#[derive(Deserialize)]
struct MemberToml {
    name: String,
    share: String,
    capital_account: Option<String>,
    distribution_account: Option<String>,
    files_jointly_with: Option<String>,
}

#[derive(Default, Deserialize)]
struct BooksSection {
    receipt_threshold: Option<String>,
    #[serde(default)]
    receipt_required_accounts: Vec<String>,
    #[serde(default)]
    receipt_exempt_accounts: Vec<String>,
    accounting_basis: Option<String>,
    close_into: Option<String>,
    #[serde(default)]
    close_sweep: Vec<String>,
    #[serde(default)]
    cash_accounts: Vec<String>,
    #[serde(default)]
    financing_accounts: Vec<String>,
    #[serde(default)]
    investing_accounts: Vec<String>,
    asset_tag_prefix: Option<String>,
    parties: Option<String>,
}

/// Parse a share: "50%" or "0.5".
fn parse_share(name: &str, s: &str) -> Result<Decimal, String> {
    let s = s.trim();
    let bad = || format!("member {name}: share {s:?} must be like \"50%\" or \"0.5\"");
    let share = match s.strip_suffix('%') {
        Some(pct) => pct.trim().parse::<Decimal>().map_err(|_| bad())? / Decimal::from(100),
        None => s.parse::<Decimal>().map_err(|_| bad())?,
    };
    if share <= Decimal::ZERO || share > Decimal::ONE {
        return Err(bad());
    }
    Ok(share)
}

/// Parse `"MM-DD"`: the first day of a month (a fiscal year ends on the
/// last day of a month: IRS Pub. 538, docs/spec/sources/
/// irs-periods-and-methods.md).
fn parse_month_day(s: &str) -> Result<(u32, u32), String> {
    let bad = || format!("fiscal_year_start {s:?}: expected \"MM-DD\", e.g. \"01-01\"");
    let (m, d) = s.split_once('-').ok_or_else(bad)?;
    let (m, d): (u32, u32) = (m.parse().map_err(|_| bad())?, d.parse().map_err(|_| bad())?);
    if !(1..=12).contains(&m) {
        return Err(bad());
    }
    if d != 1 {
        return Err(format!(
            "fiscal_year_start {s:?}: a fiscal year starts on the first of a month (it ends on the last day of one: IRS Pub. 538)"
        ));
    }
    Ok((m, d))
}

/// Account codes as written, trimmed; a blank one is refused.
fn codes(key: &str, list: Vec<String>) -> Result<Vec<String>, String> {
    list.into_iter()
        .map(|c| {
            let c = c.trim().to_string();
            if c.is_empty() {
                Err(format!("{key}: an account code is blank"))
            } else {
                Ok(c)
            }
        })
        .collect()
}

/// The receipt policy in force: `config_json`'s `receipt_policy` (the
/// text of an older books dir's `config.json`; `None`: no such file) when
/// it sets one, else `[books] receipt_threshold`, else the default
/// ($25.00); validated (crate::receipt_policy INVARIANT 4).
pub fn effective_receipt_policy_text(
    config_json: Option<&str>,
    settings: &BooksSettings,
) -> Result<ReceiptPolicy, String> {
    #[derive(Deserialize)]
    struct ConfigJson {
        #[serde(default)]
        receipt_policy: Option<ReceiptPolicy>,
    }
    let from_json = match config_json {
        Some(raw) => {
            serde_json::from_str::<ConfigJson>(raw)
                .map_err(|e| format!("bad config: {e}"))?
                .receipt_policy
        }
        None => None,
    };
    let policy = match from_json {
        Some(p) => p,
        None => ReceiptPolicy {
            require_receipts_above: settings
                .receipt_threshold
                .clone()
                .unwrap_or_else(|| ledger_core::settings::DEFAULT_THRESHOLD.to_string()),
            receipt_required_accounts: settings.receipt_required_accounts.clone(),
            receipt_exempt_accounts: settings.receipt_exempt_accounts.clone(),
        },
    };
    policy.validate()?;
    Ok(policy)
}

/// Parse `wanderbooks.toml` text.
///
/// ```text
/// GOAL: read the company's settings, refusing any the books can't honor
///       rather than guessing.
/// SOURCE: IRS Pub. 538 (docs/spec/sources/irs-periods-and-methods.md:
///         a fiscal year ends on the last day of a month); Treas. Reg.
///         §301.7701-3 and the Schedule C instructions
///         (docs/spec/sources/irs-entity-classification.md); IRC §704(a)
///         (shares from the agreement: docs/spec/sources/irs-partnerships.md).
/// INVARIANTS:
///   1. Every setting is optional; an empty file is a calendar-year,
///      accrual-basis "Unnamed company" with no members.
///   2. fiscal_year_start MUST be the first of a month ("MM-01").
///   3. Members: each MUST have a name and a capital account, names and
///      capital accounts MUST be distinct (and no member's distributions
///      account another's capital), and shares (each in (0, 1], "50%" or
///      "0.5") MUST sum to exactly 1.
///   4. tax_form wins over tax_classification (which is then not read);
///      a classification is read by whole words, ignoring case, and MUST
///      name exactly one return (source table). tax_form, basis, and
///      classification values ignore case.
///   5. receipt_threshold MUST be a decimal at least zero.
///   6. Account codes (cash, financing, investing, close_into,
///      close_sweep, members' capital and distributions) are trimmed; a
///      blank one is refused (a blank distributions account means none). close_into is
///      refused with members (a close goes to their capital accounts).
///   7. profile holds every simple [company] value in file order:
///      strings as written, numbers, booleans, and dates in TOML's
///      spelling; tables and arrays (members) are left out.
///   8. NEVER accept a file that would be read differently than written:
///      an unknown basis, tax form, or classification is refused.
/// ```
pub fn parse(text: &str) -> Result<BooksSettings, String> {
    let raw: BooksToml = toml::from_str(text).map_err(|e| e.to_string())?;
    let mut company = Company::default();
    if let Some(name) = raw.company.name.filter(|n| !n.trim().is_empty()) {
        company.name = name.trim().to_string();
    }
    if let Some(fy) = raw.company.fiscal_year_start {
        company.fiscal_year_start = parse_month_day(fy.trim())?;
    }
    for m in raw.company.members {
        let share = parse_share(&m.name, &m.share)?;
        let capital_account = m
            .capital_account
            .filter(|c| !c.trim().is_empty())
            .ok_or_else(|| format!("member {}: capital_account is required", m.name))?;
        company.members.push(Member {
            name: m.name.trim().to_string(),
            share,
            capital_account: capital_account.trim().to_string(),
            distribution_account: m
                .distribution_account
                .map(|d| d.trim().to_string())
                .filter(|d| !d.is_empty()),
            files_jointly_with: m
                .files_jointly_with
                .map(|d| d.trim().to_string())
                .filter(|d| !d.is_empty()),
        });
    }
    for (i, m) in company.members.iter().enumerate() {
        if m.name.is_empty() {
            return Err(format!("member {}: name is blank", i + 1));
        }
        for other in &company.members[..i] {
            if other.name == m.name {
                return Err(format!("member {} is listed twice", m.name));
            }
            if other.capital_account == m.capital_account {
                return Err(format!(
                    "members {} and {} share capital account {}",
                    other.name, m.name, m.capital_account
                ));
            }
        }
        for other in &company.members {
            if other.distribution_account.as_deref() == Some(m.capital_account.as_str()) {
                return Err(format!(
                    "{}'s distributions account {} is {}'s capital account",
                    other.name, m.capital_account, m.name
                ));
            }
        }
    }
    // files_jointly_with names another member, and both say so.
    for m in &company.members {
        if let Some(j) = &m.files_jointly_with {
            if *j == m.name {
                return Err(format!(
                    "member {}: files_jointly_with names themself",
                    m.name
                ));
            }
            match company.members.iter().find(|o| o.name == *j) {
                None => {
                    return Err(format!(
                        "member {}: files_jointly_with {j:?} isn't a member",
                        m.name
                    ));
                }
                Some(o) if o.files_jointly_with.as_deref() != Some(m.name.as_str()) => {
                    return Err(format!(
                        "member {} files jointly with {j}, but {j}'s files_jointly_with doesn't name {}: set it on both",
                        m.name, m.name
                    ));
                }
                Some(_) => {}
            }
        }
    }
    if !company.members.is_empty() {
        let total: Decimal = company.members.iter().map(|m| m.share).sum();
        if total != Decimal::ONE {
            return Err(format!("member shares sum to {total}, not 100%"));
        }
    }
    company.tax_form =
        match (&raw.company.tax_form, &raw.company.tax_classification) {
            (Some(f), _) => Some(ledger_core::TaxForm::parse(f).ok_or_else(|| {
                format!("tax_form {f:?}: expected schedule_c, 1065, 1120s, or 1120")
            })?),
            (None, Some(c)) => Some(ledger_core::settings::form_for_classification(c).ok_or_else(|| {
                format!(
                    "tax_classification {c:?}: expected partnership, S corporation, C corporation, or disregarded entity (or set tax_form)"
                )
            })?),
            (None, None) => None,
        };
    if !company.members.is_empty() && raw.books.close_into.is_some() {
        return Err(
            "close_into is for single-owner businesses; with [[company.members]] a close goes to each member's capital account"
                .to_string(),
        );
    }
    company.close_into = match raw.books.close_into {
        Some(c) => Some(codes("close_into", vec![c])?.remove(0)),
        None => None,
    };
    company.close_sweep = codes("close_sweep", raw.books.close_sweep)?;
    if let Some(basis) = raw.books.accounting_basis {
        company.basis = match basis.trim().to_lowercase().as_str() {
            "accrual" => "Accrual".to_string(),
            "cash" => "Cash".to_string(),
            other => {
                return Err(format!(
                    "accounting_basis {other:?}: expected accrual or cash"
                ));
            }
        };
    }
    let receipt_threshold = match raw.books.receipt_threshold {
        Some(t) => {
            let v = decimal(t.trim())
                .ok_or_else(|| format!("receipt_threshold {t:?} is not a decimal"))?;
            if v.is_sign_negative() && !v.is_zero() {
                return Err(format!("receipt_threshold {t:?} is below zero"));
            }
            Some(t.trim().to_string())
        }
        None => None,
    };
    let table: toml::Table = toml::from_str(text).map_err(|e| e.to_string())?;
    if let Some(toml::Value::Table(c)) = table.get("company") {
        company.profile = c
            .iter()
            .filter_map(|(k, v)| {
                let s = match v {
                    toml::Value::String(s) => s.clone(),
                    toml::Value::Integer(i) => i.to_string(),
                    toml::Value::Float(f) => f.to_string(),
                    toml::Value::Boolean(b) => b.to_string(),
                    toml::Value::Datetime(d) => d.to_string(),
                    _ => return None,
                };
                Some((k.clone(), s))
            })
            .collect();
    }
    // The key file is no books setting (`codec` notes it), but an empty
    // one is still a broken file.
    if raw.vault.key_file.is_some_and(|p| p.trim().is_empty()) {
        return Err("[vault] key_file is empty".into());
    }
    let timezone = match raw.company.timezone {
        Some(z) => {
            let key = ledger_core::settings::key("company.timezone").expect("a known key");
            let v = ledger_core::settings::check(key, &toml_json(&z))?;
            v.as_str().map(str::to_string)
        }
        None => None,
    };
    Ok(BooksSettings {
        company,
        receipt_threshold,
        receipt_required_accounts: codes(
            "receipt_required_accounts",
            raw.books.receipt_required_accounts,
        )?,
        receipt_exempt_accounts: codes(
            "receipt_exempt_accounts",
            raw.books.receipt_exempt_accounts,
        )?,
        timezone,
        cash_accounts: codes("cash_accounts", raw.books.cash_accounts)?,
        financing_accounts: codes("financing_accounts", raw.books.financing_accounts)?,
        investing_accounts: codes("investing_accounts", raw.books.investing_accounts)?,
        asset_tag_prefix: match raw.books.asset_tag_prefix {
            Some(p)
                if !p.is_empty()
                    && p.len() <= 8
                    && p.chars().all(|c| c.is_ascii_alphanumeric()) =>
            {
                Some(p)
            }
            Some(p) => {
                return Err(format!(
                    "[books] asset_tag_prefix {p:?}: 1 to 8 letters or digits"
                ));
            }
            None => None,
        },
        parties: match raw.books.parties.as_deref() {
            None | Some("suggest") => PartyPolicy::Suggest,
            Some("off") => PartyPolicy::Off,
            Some("require") | Some("required") => PartyPolicy::Require,
            Some(other) => {
                return Err(format!(
                    "[books] parties {other:?}: \"off\", \"suggest\", or \"require\""
                ));
            }
        },
    })
}

fn toml_json(s: &str) -> serde_json::Value {
    serde_json::Value::String(s.to_string())
}

#[cfg(test)]
mod tests {
    use super::*;
    use chrono::NaiveDate;

    /// files_jointly_with: names another member, on both sides.
    #[test]
    fn files_jointly_with() {
        let m = |a: &str, b: &str| {
            format!(
                "[company]\nname = \"X\"\n[[company.members]]\nname = \"A\"\nshare = \"50%\"\ncapital_account = \"3000\"\n{a}\n[[company.members]]\nname = \"B\"\nshare = \"50%\"\ncapital_account = \"3001\"\n{b}\n"
            )
        };
        let ok = parse(&m(
            "files_jointly_with = \"B\"",
            "files_jointly_with = \"A\"",
        ))
        .unwrap();
        assert_eq!(
            ok.company.members[0].files_jointly_with.as_deref(),
            Some("B")
        );
        assert!(
            parse(&m("files_jointly_with = \"B\"", ""))
                .unwrap_err()
                .contains("set it on both")
        );
        assert!(
            parse(&m("files_jointly_with = \"C\"", ""))
                .unwrap_err()
                .contains("isn't a member")
        );
        assert!(
            parse(&m("files_jointly_with = \"A\"", ""))
                .unwrap_err()
                .contains("themself")
        );
        assert_eq!(
            parse(&m("", "")).unwrap().company.members[1].files_jointly_with,
            None
        );
    }

    /// `[books] parties`: suggest by default; off, suggest, require (and
    /// "required") parse; anything else is refused, naming the choices.
    #[test]
    fn parties_policy() {
        let base = "[company]\nname = \"Acme LLC\"\n[books]\n";
        assert_eq!(parse(base).unwrap().parties, PartyPolicy::Suggest);
        for (v, want) in [
            ("off", PartyPolicy::Off),
            ("suggest", PartyPolicy::Suggest),
            ("require", PartyPolicy::Require),
            ("required", PartyPolicy::Require),
        ] {
            let s = parse(&format!("{base}parties = \"{v}\"\n")).unwrap();
            assert_eq!(s.parties, want, "{v}");
        }
        let e = parse(&format!("{base}parties = \"always\"\n")).unwrap_err();
        assert!(e.contains("require"), "{e}");
    }

    fn d(y: i32, m: u32, day: u32) -> NaiveDate {
        NaiveDate::from_ymd_opt(y, m, day).unwrap()
    }

    #[test]
    fn calendar_year_by_default() {
        let c = parse("").unwrap().company;
        assert_eq!(c.fiscal_year_start, (1, 1));
        assert_eq!(
            c.fiscal_year_containing(d(2026, 10, 11)),
            (d(2026, 1, 1), d(2026, 12, 31))
        );
        assert_eq!(
            c.fiscal_year_containing(d(2026, 1, 1)),
            (d(2026, 1, 1), d(2026, 12, 31))
        );
    }

    #[test]
    fn a_july_fiscal_year_spans_two_calendar_years() {
        let c = parse("[company]\nfiscal_year_start = \"07-01\"\n")
            .unwrap()
            .company;
        assert_eq!(
            c.fiscal_year_containing(d(2026, 3, 15)),
            (d(2025, 7, 1), d(2026, 6, 30))
        );
        assert_eq!(
            c.fiscal_year_containing(d(2026, 7, 1)),
            (d(2026, 7, 1), d(2027, 6, 30))
        );
        assert_eq!(
            c.fiscal_year_containing(d(2026, 6, 30)),
            (d(2025, 7, 1), d(2026, 6, 30))
        );
    }

    #[test]
    fn reads_the_scaffolded_file() {
        let s = parse(
            "[company]\nname = \"Fernhill Labs LLC\"\nentity_type = \"x\"\nfiscal_year_start = \"01-01\"\n\n[books]\ndata_dir = \"books-data\"\nreceipt_threshold = \"25.00\"\n",
        )
        .unwrap();
        assert_eq!(s.company.name, "Fernhill Labs LLC");
        assert_eq!(s.receipt_threshold.as_deref(), Some("25.00"));
        // An empty name (fresh scaffold) keeps the placeholder.
        assert_eq!(
            parse("[company]\nname = \"\"\n").unwrap().company.name,
            "Unnamed company"
        );
    }

    #[test]
    fn keeps_the_whole_profile_in_order() {
        let s = parse(
            "[company]\nname = \"Acme LLC\"\nein = \"12-3456789\"\nformed = \"2026-10-04\"\n[books]\ncash_accounts = [\"1000\", \"1010\"]\nfinancing_accounts = [\"2100\"]\ninvesting_accounts = [\"1400\"]\n",
        )
        .unwrap();
        assert_eq!(
            s.company.profile,
            [
                ("name".to_string(), "Acme LLC".to_string()),
                ("ein".to_string(), "12-3456789".to_string()),
                ("formed".to_string(), "2026-10-04".to_string()),
            ]
        );
        assert_eq!(s.cash_accounts, ["1000", "1010"]);
        assert_eq!(s.financing_accounts, ["2100"]);
        assert_eq!(s.investing_accounts, ["1400"]);
    }

    #[test]
    fn reads_members_and_basis() {
        let s = parse(
            "[company]\n[[company.members]]\nname = \"Tobin Harlow\"\nshare = \"50%\"\ncapital_account = \"3000\"\n[[company.members]]\nname = \"Morgan Ellis\"\nshare = \"0.5\"\ncapital_account = \"3001\"\n[books]\naccounting_basis = \"cash\"\n",
        )
        .unwrap();
        let half = Decimal::new(5, 1);
        assert_eq!(
            s.company.members,
            vec![
                Member {
                    name: "Tobin Harlow".into(),
                    share: half,
                    capital_account: "3000".into(),
                    distribution_account: None,
                    files_jointly_with: None,
                },
                Member {
                    name: "Morgan Ellis".into(),
                    share: half,
                    capital_account: "3001".into(),
                    distribution_account: None,
                    files_jointly_with: None,
                },
            ]
        );
        assert_eq!(s.company.basis, "Cash");
        assert_eq!(parse("").unwrap().company.basis, "Accrual");
        // Shares must add up; every member needs a capital account.
        let two = |a: &str, b: &str| {
            format!(
                "[company]\n[[company.members]]\nname = \"A\"\nshare = \"{a}\"\ncapital_account = \"3000\"\n[[company.members]]\nname = \"B\"\nshare = \"{b}\"\ncapital_account = \"3001\"\n"
            )
        };
        assert!(parse(&two("50%", "40%")).is_err());
        assert!(parse(&two("60%", "40%")).is_ok());
        assert!(parse("[company]\n[[company.members]]\nname = \"A\"\nshare = \"100%\"\n").is_err());
        assert!(parse("[books]\naccounting_basis = \"modified\"\n").is_err());
    }

    #[test]
    fn tax_form_from_setting_or_classification() {
        use ledger_core::TaxForm;
        let form = |toml: &str| parse(toml).unwrap().company.tax_form;
        assert_eq!(
            form("[company]\ntax_form = \"1120s\"\n"),
            Some(TaxForm::Form1120S)
        );
        assert_eq!(
            form("[company]\ntax_classification = \"partnership\"\n"),
            Some(TaxForm::Form1065)
        );
        assert_eq!(
            form("[company]\ntax_classification = \"S corporation\"\n"),
            Some(TaxForm::Form1120S)
        );
        assert_eq!(
            form("[company]\ntax_classification = \"disregarded entity\"\n"),
            Some(TaxForm::ScheduleC)
        );
        assert_eq!(
            form("[company]\ntax_classification = \"partnership\"\ntax_form = \"1120\"\n"),
            Some(TaxForm::Form1120)
        );
        assert_eq!(form(""), None);
        assert!(parse("[company]\ntax_form = \"990\"\n").is_err());
    }

    #[test]
    fn rejects_bad_settings() {
        assert!(parse("[company]\nfiscal_year_start = \"02-29\"\n").is_err());
        assert!(parse("[company]\nfiscal_year_start = \"13-01\"\n").is_err());
        assert!(parse("[company]\nfiscal_year_start = \"Jan 1\"\n").is_err());
        assert!(parse("[books]\nreceipt_threshold = \"25 dollars\"\n").is_err());
    }
}