Also patched decimal multiplication

alasco-tech · Jun 27, 2024 · 844eb37 · 844eb37
1 parent 2110f9a
commit 844eb37
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Showing 5 changed files with 51 additions and 23 deletions.
diff --git a/pytests/test_money.py b/pytests/test_money.py
@@ -136,9 +136,12 @@ def test_advanced_negation(decimal):
     assert str(Money(decimal).amount) == "-0"
 
 
-@pytest.mark.parametrize("left", ["0", "-0"])
-@pytest.mark.parametrize("right", ["0", "-0"])
-def test_add_with_negative_zeros(left, right):
+OPERANDS = ["0", "-0", "1", "-1"]
+
+
+@pytest.mark.parametrize("left", OPERANDS)
+@pytest.mark.parametrize("right", OPERANDS)
+def test_add_with_operands(left, right):
     expected = Decimal(left) + Decimal(right)
 
     money_left = Money(left)
@@ -152,9 +155,9 @@ def test_add_with_negative_zeros(left, right):
     assert str((money_left + money_right).amount) == str(expected)
 
 
-@pytest.mark.parametrize("left", ["0", "-0"])
-@pytest.mark.parametrize("right", ["0", "-0"])
-def test_sub_with_negative_zeros(left, right):
+@pytest.mark.parametrize("left", OPERANDS)
+@pytest.mark.parametrize("right", OPERANDS)
+def test_sub_with_operands(left, right):
     expected = Decimal(left) - Decimal(right)
 
     money_left = Money(left)
@@ -168,6 +171,21 @@ def test_sub_with_negative_zeros(left, right):
     assert str((money_left - money_right).amount) == str(expected)
 
 
+@pytest.mark.parametrize("left", OPERANDS)
+@pytest.mark.parametrize("right", OPERANDS)
+def test_mult_with_operands(left, right):
+    expected = Decimal(left) * Decimal(right)
+
+    money_left = Money(left)
+    money_right = Money(right)
+
+    assert str(money_left.amount) == str(left)
+    assert str(money_right.amount) == str(right)
+
+    assert str((money_left * Decimal(right)).amount) == str(expected)
+    assert str((Decimal(left) * money_right).amount) == str(expected)
+
+
 def test_equality_to_other_types():
     x = Money(0)
     assert x != None  # noqa: E711

diff --git a/src/decimals.rs b/src/decimals.rs
@@ -36,6 +36,21 @@ pub fn decimal_add(left: Decimal, right: Decimal) -> Decimal {
     }
 }
 
+// Multiplies decimals the way of Python
+pub fn decimal_mult(left: Decimal, right: Decimal) -> Decimal {
+    let zero = Decimal::new(0, 0);
+
+    if left.abs() == zero || right.abs() == zero {
+        if left.is_sign_negative() == right.is_sign_negative() {
+            zero
+        } else {
+            -zero
+        }
+    } else {
+        left * right
+    }
+}
+
 // Rounds decimals the way of Python
 pub fn round(value: Decimal, scale: i32, round_up: bool) -> Decimal {
     let strategy = if round_up {

diff --git a/src/money.rs b/src/money.rs
@@ -133,14 +133,9 @@ impl Money {
 
     fn __mul__(&self, other: Bound<PyAny>) -> PyResult<Self> {
         if let Ok(other_decimal) = get_decimal(other) {
-            if other_decimal == Decimal::new(-1, 0) {
-                // Hack for minus zero
-                Ok(self.__neg__())
-            } else {
-                Ok(Self {
-                    amount: self.amount * other_decimal,
-                })
-            }
+            Ok(Self {
+                amount: decimal_mult(self.amount, other_decimal),
+            })
         } else {
             Err(pyo3::exceptions::PyTypeError::new_err(
                 "Unsupported operand",

diff --git a/src/money_vat.rs b/src/money_vat.rs
@@ -7,7 +7,7 @@ use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};
 use std::str::FromStr;
 
-use crate::decimals::{decimal_add, get_decimal};
+use crate::decimals::{decimal_add, decimal_mult, get_decimal};
 use crate::money::{Money, MONEY_PRECISION};
 use crate::money_vat_ratio::MoneyWithVATRatio;
 
@@ -75,7 +75,7 @@ impl MoneyWithVAT {
         }
 
         for rate in Self::known_vat_rates() {
-            let vat = rate * self.net.amount;
+            let vat = decimal_mult(rate, self.net.amount);
             let vat_diff = (decimal_add(vat, -self.tax.amount)).abs();
             if vat_diff < boundary {
                 return rate;
@@ -218,23 +218,23 @@ impl MoneyWithVAT {
 
     fn __mul__(&self, other: Bound<PyAny>) -> PyResult<Self> {
         if let Ok(other_ratio) = other.extract::<MoneyWithVATRatio>() {
-            let net_value = other_ratio.net_ratio * self.net.amount;
+            let net_value = decimal_mult(other_ratio.net_ratio, self.net.amount);
             Ok(Self {
                 net: Money { amount: net_value },
                 tax: Money {
                     amount: decimal_add(
-                        other_ratio.gross_ratio * self.get_gross().amount,
+                        decimal_mult(other_ratio.gross_ratio, self.get_gross().amount),
                         -net_value,
                     ),
                 },
             })
         } else if let Ok(other_decimal) = get_decimal(other) {
             Ok(Self {
                 net: Money {
-                    amount: self.net.amount * other_decimal,
+                    amount: decimal_mult(self.net.amount, other_decimal),
                 },
                 tax: Money {
-                    amount: self.tax.amount * other_decimal,
+                    amount: decimal_mult(self.tax.amount, other_decimal),
                 },
             })
         } else {

diff --git a/src/money_vat_ratio.rs b/src/money_vat_ratio.rs
@@ -4,7 +4,7 @@ use pyo3::types::{PyCFunction, PyDict, PyTuple};
 use rust_decimal::prelude::FromPrimitive;
 use rust_decimal::Decimal;
 
-use crate::decimals::{decimal_add, get_decimal};
+use crate::decimals::{decimal_add, decimal_mult, get_decimal};
 
 #[pyclass]
 #[derive(Debug, Clone)]
@@ -81,8 +81,8 @@ impl MoneyWithVATRatio {
         let other_decimal = Decimal::from_f64(other).unwrap();
 
         Self {
-            net_ratio: self.net_ratio * other_decimal,
-            gross_ratio: self.gross_ratio * other_decimal,
+            net_ratio: decimal_mult(self.net_ratio, other_decimal),
+            gross_ratio: decimal_mult(self.gross_ratio, other_decimal),
         }
     }