rudb 0.2.8

//! `read_csv` from SQL, and the replacement scan over a `.csv` or a `.tsv` name.
//!
//! The fixtures are `rudb-csv`'s, referred to across the workspace rather than copied. The big one
//! holds the same 4096 rows as the Parquet fixture, written out by the same DuckDB query, so an
//! answer that differs between the two readers shows up as a number that differs between this file
//! and `tests/parquet.rs` rather than as nothing at all.
//!
//! What is asserted here is the SQL and the sniffing that SQL cannot see any other way. The
//! splitting and the type ladder have their own tests one layer down.

use rudb::Database;
use rudb_common::Value;

/// The path of a fixture, as a SQL string literal.
fn fixture(name: &str) -> String {
    format!("'{}/../rudb-csv/testdata/{name}'", env!("CARGO_MANIFEST_DIR"))
}

/// `SELECT <what> FROM read_csv(<mixed.csv>)`, as one value.
fn one(what: &str) -> Value {
    let database = Database::new();
    let sql = format!("SELECT {what} FROM read_csv({})", fixture("mixed.csv"));
    database.value(&sql).unwrap_or_else(|error| panic!("{sql} failed: {error}"))
}

#[test]
fn counting_the_rows_of_a_file_is_the_number_of_rows_in_it() {
    // 4096 and not 4097, which is what a reader that took the header line for a row would say.
    assert_eq!(one("count(*)"), Value::BigInt(4096));
}

#[test]
fn the_columns_are_the_names_and_the_types_duckdb_sniffs_for_the_same_file() {
    let database = Database::new();
    let sql = format!("SELECT * FROM read_csv({})", fixture("mixed.csv"));
    let result = database.query(&sql).expect("runs");
    assert_eq!(result.len(), 4096);
    assert_eq!(result.names(), ["a", "b", "s", "d", "flag", "day", "t"]);
    let types: Vec<String> = result.types().iter().map(ToString::to_string).collect();
    // `a` is a BIGINT and not an INTEGER, which is the one place this disagrees with the Parquet
    // fixture holding the same numbers. A CSV file does not say how wide its integers are and the
    // sniffer's rung is BIGINT, so this is DuckDB's answer rather than a loss of information.
    assert_eq!(types, ["BIGINT", "BIGINT", "VARCHAR", "DOUBLE", "BOOLEAN", "DATE", "TIMESTAMP"]);
}

#[test]
fn the_first_row_is_the_one_duckdb_reads_from_the_same_bytes() {
    let database = Database::new();
    let sql = format!("SELECT * FROM read_csv({}) LIMIT 1", fixture("mixed.csv"));
    let result = database.query(&sql).expect("runs");
    let row: Vec<Value> = (0..result.width()).map(|at| result.value_at(0, at)).collect();
    assert_eq!(
        row,
        vec![
            Value::BigInt(0),
            Value::BigInt(0),
            Value::Null,
            Value::Double(0.0),
            Value::Boolean(true),
            Value::Date(0),
            Value::Timestamp(1_373_882_400_000_000),
        ]
    );
}

#[test]
fn the_sums_are_the_sums_duckdb_reports_for_the_same_file() {
    assert_eq!(one("sum(a)"), Value::HugeInt(195_783));
    assert_eq!(one("sum(b)"), Value::HugeInt(2_002_560_000));
    assert_eq!(one("sum(d)"), Value::Double(193_536.0));
    assert_eq!(one("min(day)"), Value::Date(0));
    assert_eq!(one("max(day)"), Value::Date(999));
}

#[test]
fn an_empty_field_is_a_null_and_not_an_empty_string() {
    // The one place a CSV file is ambiguous and DuckDB picks a side. 586 of the 4096 rows have
    // nothing between the two commas, and every one of them is a null.
    assert_eq!(one("count(s)"), Value::BigInt(3510));
    let database = Database::new();
    let sql = format!("SELECT count(*) FROM read_csv({}) WHERE s IS NULL", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(586));
}

#[test]
fn a_where_clause_over_a_file_filters_the_rows_it_read() {
    let database = Database::new();
    let sql = format!("SELECT count(*) FROM read_csv({}) WHERE flag", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(2048));
    let sql = format!("SELECT count(*) FROM read_csv({}) WHERE a < 10", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(430));
}

#[test]
fn an_aggregate_over_a_text_column_groups_by_its_values() {
    let database = Database::new();
    let sql = format!(
        "SELECT s, count(*) FROM read_csv({}) WHERE s IS NOT NULL GROUP BY s ORDER BY s",
        fixture("mixed.csv")
    );
    let result = database.query(&sql).expect("runs");
    assert_eq!(result.len(), 5, "tag0 to tag4");
    assert_eq!(result.value_at(0, 0), Value::Varchar("tag0".into()));
}

#[test]
fn read_csv_auto_reads_the_same_file_under_duckdbs_older_name_for_the_function() {
    let database = Database::new();
    let sql = format!("SELECT count(*) FROM read_csv_auto({})", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(4096));
}

#[test]
fn an_alias_renames_the_call_and_not_its_columns() {
    let database = Database::new();
    let sql = format!("SELECT c.a FROM read_csv({}) AS c LIMIT 1", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(0));
}

#[test]
fn a_file_with_no_header_gets_the_names_duckdb_gives_it() {
    let database = Database::new();
    let sql = format!("SELECT * FROM read_csv({})", fixture("noheader.csv"));
    let result = database.query(&sql).expect("runs");
    assert_eq!(result.names(), ["column0", "column1", "column2"]);
    assert_eq!(result.len(), 3);
    let types: Vec<String> = result.types().iter().map(ToString::to_string).collect();
    assert_eq!(types, ["BIGINT", "VARCHAR", "DOUBLE"]);
}

#[test]
fn a_tab_separated_file_is_worked_out_from_its_bytes_and_not_from_its_name() {
    let database = Database::new();
    let sql = format!("SELECT * FROM read_csv({})", fixture("punctuation.tsv"));
    let result = database.query(&sql).expect("runs");
    assert_eq!(result.names(), ["name", "note"]);
    assert_eq!(result.len(), 3);
    assert_eq!(result.value_at(0, 1), Value::Varchar("holds\ta tab".into()));
    assert_eq!(result.value_at(1, 1), Value::Varchar("holds\na newline".into()));
    assert_eq!(result.value_at(2, 1), Value::Varchar("says \"hi\"".into()));
}

#[test]
fn a_file_that_is_not_there_fails_at_bind_time_with_duckdbs_message() {
    let database = Database::new();
    let error = database.query("SELECT * FROM read_csv('/nowhere/at/all.csv')").unwrap_err();
    assert_eq!(error.message(), "No files found that match the pattern \"/nowhere/at/all.csv\"");
}

#[test]
fn a_path_that_is_not_a_string_does_not_become_one() {
    let database = Database::new();
    let error = database.query("SELECT * FROM read_csv(3)").unwrap_err();
    assert!(error.message().contains("read_csv(INTEGER)"), "{error}");
}

#[test]
fn a_csv_name_where_a_table_name_goes_reads_the_file() {
    let database = Database::new();
    let sql = format!("SELECT count(*) FROM {}", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(4096));
}

#[test]
fn a_tsv_name_goes_to_the_same_reader_as_a_csv_one() {
    let database = Database::new();
    let sql = format!("SELECT count(*) FROM {}", fixture("punctuation.tsv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(3));
}

#[test]
fn the_columns_of_a_replaced_file_answer_to_the_stem_of_its_name() {
    let database = Database::new();
    let sql = format!("SELECT mixed.a FROM {} LIMIT 1", fixture("mixed.csv"));
    assert_eq!(database.value(&sql).expect("runs"), Value::BigInt(0));
}

#[test]
fn a_csv_file_that_is_not_there_is_the_file_error_and_not_the_table_one() {
    // The extension is read before the file is looked for, so a name that says csv gets the
    // reader's complaint about the file rather than the catalog's complaint about the name.
    let database = Database::new();
    let error = database.query("SELECT * FROM '/nowhere/at/all.csv'").unwrap_err();
    assert_eq!(error.message(), "No files found that match the pattern \"/nowhere/at/all.csv\"");
}

#[test]
fn a_file_that_is_there_and_has_an_extension_nothing_reads_says_so() {
    // The README of the fixture directory, which exists and is not a file any reader here takes.
    // A name with the same extension that is not there is the catalog error instead, which is the
    // other half of the rule and is asserted next to it.
    let database = Database::new();
    let sql = format!("SELECT * FROM {}", fixture("README.md"));
    let error = database.query(&sql).unwrap_err();
    assert!(
        error.message().starts_with("No extension found that is capable of reading the file"),
        "{error}"
    );
    assert!(error.message().contains("read_csv, read_json or read_parquet"), "{error}");
    let error = database.query("SELECT * FROM 'nowhere.md'").unwrap_err();
    assert_eq!(error.message(), "Table with name nowhere.md does not exist!");
}

#[test]
fn a_file_can_be_loaded_into_a_table_and_queried_from_there() {
    let mut database = Database::new();
    let sql = format!("CREATE TABLE loaded AS SELECT a, s FROM read_csv({})", fixture("mixed.csv"));
    database.execute(&sql).expect("loads");
    assert_eq!(database.value("SELECT count(*) FROM loaded").expect("runs"), Value::BigInt(4096));
    assert_eq!(database.value("SELECT sum(a) FROM loaded").expect("runs"), Value::HugeInt(195_783));
    assert_eq!(database.value("SELECT count(s) FROM loaded").expect("runs"), Value::BigInt(3510));
}