Properly encode BigDecimal values whose first digit is 10k

When serializing a numeric column, we need to take a decimal value and
convert it to a list of its digits in base 10k. The serialization code
had a bug when the first digit was exactly `10000`, resulting in the
digits being `[10000, ...]` instead of `[1, 0, ...]`. This bug only
affected the integral part, as the decimal portion uses different logic
in order ot strip trailing zeroes.

Fixes diesel-rs#1044.

CHANGELOG.md

@@ -4,10 +4,19 @@ All user visible changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/), as described
 for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/text/1105-api-evolution.md)
 
+## Unreleased
+
 ### Added
 
 * Added helper types for inner join and left outer join
 
+### Fixed
+
+* `BigDecimal` now properly encodes numbers starting with `10000` on postgres.
+  See [issue #1044][] for details.
+
+[issue #1044]: https://github.com/diesel-rs/diesel/issues/1044
+
 ## [0.15.1] - 2017-07-24
 
 * No changes to public API

diesel/src/pg/types/numeric.rs

@@ -26,7 +26,7 @@ mod bigdecimal {
 
         let mut integer_part = absolute.to_bigint().expect("Can always take integer part of BigDecimal");
 
-        while ten_k < integer_part {
+        while ten_k <= integer_part {
             weight += 1;
             // digit is integer_part REM 10_000
             let (div, digit) = integer_part.div_rem(&ten_k);

diesel_tests/tests/types.rs

@@ -441,25 +441,50 @@ fn pg_mysql_numeric_bigdecimal_to_sql() {
     }
 
     quickcheck(correct_rep as fn(u64, u64) -> bool);
+
+    let test_values = vec![
+        "1.0",
+        "141.0",
+        "-1.0",
+        // Larger than u64
+        "18446744073709551616",
+        // Powers of 10k (numeric is represented in base 10k)
+        "10000",
+        "100000000",
+        "1.100001",
+        "10000.100001",
+    ];
+
+    for value in test_values {
+        let expected = format!("'{}'::numeric", value);
+        let value = value.parse::<BigDecimal>().unwrap();
+        query_to_sql_equality::<Numeric, _>(&expected, value);
+    }
 }
 
 #[test]
 #[cfg(feature = "postgres")]
 fn pg_numeric_bigdecimal_from_sql() {
     use self::bigdecimal::BigDecimal;
 
-    let query = "1.0::numeric";
-    let expected_value: BigDecimal = "1.0".parse().expect("Could not parse to a BigDecimal");
-    assert_eq!(expected_value, query_single_value::<Numeric, BigDecimal>(query));
-
-    let query = "141.00::numeric";
-    let expected_value: BigDecimal = "141.00".parse().expect("Could not parse to a BigDecimal");
-    assert_eq!(expected_value, query_single_value::<Numeric, BigDecimal>(query));
+    let values = vec![
+        "1.0",
+        "141.0",
+        "-1.0",
+        // Larger than u64
+        "18446744073709551616",
+        // Powers of 10k (numeric is represented in base 10k)
+        "10000",
+        "100000000",
+        "1.100001",
+        "10000.100001",
+    ];
 
-    // Some non standard values:
-    let query = "18446744073709551616::numeric"; // 2^64; doesn't fit in u64
-    let expected_value: BigDecimal = "18446744073709551616.00".parse().expect("Could not parse to a BigDecimal");
-    assert_eq!(expected_value, query_single_value::<Numeric, BigDecimal>(query));
+    for value in values {
+        let query = format!("'{}'::numeric", value);
+        let expected = value.parse::<BigDecimal>().unwrap();
+        assert_eq!(expected, query_single_value::<Numeric, BigDecimal>(&query));
+    }
 }
 
 #[test]