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[test] Add more tests for multiply() #32

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Merged
forfudan merged 1 commit into from
Mar 15, 2025
Merged

[test] Add more tests for multiply() #32

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2 changes: 2 additions & 0 deletions benches/bench.mojo
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ from bench_divide import main as bench_divide
from bench_sqrt import main as bench_sqrt
from bench_from_float import main as bench_from_float
from bench_from_string import main as bench_from_string
from bench_round import main as bench_round
from bench_comparison import main as bench_comparison
from bench_exp import main as bench_exp

Expand All @@ -17,5 +18,6 @@ fn main() raises:
bench_sqrt()
bench_from_float()
bench_from_string()
bench_round()
bench_comparison()
bench_exp()
1 change: 1 addition & 0 deletions mojoproject.toml
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Expand Up @@ -33,6 +33,7 @@ debug_sqrt = "magic run package && magic run mojo tests/test_sqrt.mojo && magic
test = "magic run package && magic run mojo test tests && magic run delete_package"
t = "clear && magic run test"
test_arith = "magic run package && magic run mojo test tests/test_arithmetics.mojo && magic run delete_package"
test_multiply = "magic run package && magic run mojo test tests/test_multiply.mojo && magic run delete_package"
test_divide = "magic run package && magic run mojo test tests/test_division.mojo && magic run delete_package"
test_sqrt = "magic run package && magic run mojo test tests/test_sqrt.mojo && magic run delete_package"
test_round = "magic run package && magic run mojo test tests/test_round.mojo && magic run delete_package"
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11 changes: 6 additions & 5 deletions src/decimojo/arithmetics.mojo
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Expand Up @@ -436,12 +436,13 @@ fn multiply(x1: Decimal, x2: Decimal) raises -> Decimal:
# SPECIAL CASE: zero
# Return zero while preserving the scale
if x1_coef == 0 or x2_coef == 0:
var result = Decimal.ZERO()
var result_scale = min(combined_scale, Decimal.MAX_SCALE)
result.flags = UInt32(
(result_scale << Decimal.SCALE_SHIFT) & Decimal.SCALE_MASK
return Decimal(
0,
0,
0,
scale=min(combined_scale, Decimal.MAX_SCALE),
sign=is_negative,
)
return result

# SPECIAL CASE: Both operands have coefficient of 1
if x1_coef == 1 and x2_coef == 1:
Expand Down
172 changes: 0 additions & 172 deletions tests/test_arithmetics.mojo
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Expand Up @@ -466,175 +466,6 @@ fn test_subtract() raises:
print("Decimal subtraction tests passed!")


fn test_multiplication() raises:
print("------------------------------------------------------")
print("Testing decimal multiplication...")

# Test case 1: Simple multiplication with same scale
var a1 = Decimal("12.34")
var b1 = Decimal("5.67")
var result1 = a1 * b1
testing.assert_equal(
String(result1), "69.9678", "Simple multiplication with same scale"
)

# Test case 2: Multiplication with different scales
var a2 = Decimal("12.3")
var b2 = Decimal("5.67")
var result2 = a2 * b2
testing.assert_equal(
String(result2), "69.741", "Multiplication with different scales"
)

# Test case 3: Multiplication with negative numbers
var a3 = Decimal("12.34")
var b3 = Decimal("-5.67")
var result3 = a3 * b3
testing.assert_equal(
String(result3), "-69.9678", "Multiplication with negative number"
)

# Test case 4: Multiplication with both negative numbers
var a4 = Decimal("-12.34")
var b4 = Decimal("-5.67")
var result4 = a4 * b4
testing.assert_equal(
String(result4), "69.9678", "Multiplication with both negative numbers"
)

# Test case 5: Multiplication by zero
var a5 = Decimal("12.34")
var b5 = Decimal("0.00")
var result5 = a5 * b5
testing.assert_equal(String(result5), "0.0000", "Multiplication by zero")

# Test case 6: Multiplication by one
var a6 = Decimal("12.34")
var b6 = Decimal("1.00")
var result6 = a6 * b6
testing.assert_equal(String(result6), "12.3400", "Multiplication by one")

# Test case 7: Multiplication with large scales
var a7 = Decimal("0.0001")
var b7 = Decimal("0.0002")
var result7 = a7 * b7
testing.assert_equal(
String(result7), "0.00000002", "Multiplication with large scales"
)

# Test case 8: Multiplication resulting in scale truncation
var a8 = Decimal("0.123456789")
var b8 = Decimal("0.987654321")
var result8 = a8 * b8
testing.assert_equal(
String(result8),
"0.121932631112635269",
"Multiplication with scale truncation",
)

# Test case 9: Multiplication of large numbers
var a9 = Decimal("1234567.89")
var b9 = Decimal("9876543.21")
var result9 = a9 * b9
testing.assert_equal(
String(result9),
"12193263111263.5269",
"Multiplication of large numbers",
)

# Test case 10: Verify that a * b = b * a (commutative property)
var a10 = Decimal("123.456")
var b10 = Decimal("789.012")
var result10a = a10 * b10
var result10b = b10 * a10
testing.assert_equal(
String(result10a),
String(result10b),
"Multiplication should be commutative",
)

# Test case 11: Multiplication near precision limits
var a11 = Decimal("0." + "1" * 10)
var b11 = Decimal("0." + "1" * 18)
var result11 = a11 * b11
testing.assert_equal(
String(result11),
"0.0123456790111111110987654321",
"Multiplication near precision limits",
)

# Test case 12: Multiplication with integers
var a12 = Decimal("123")
var b12 = Decimal("456")
var result12 = a12 * b12
testing.assert_equal(
String(result12), "56088", "Multiplication with integers"
)

# Test case 13: Multiplication with powers of 10
var a13 = Decimal("12.34")
var b13 = Decimal("10")
var result13 = a13 * b13
testing.assert_equal(
String(result13), "123.40", "Multiplication by power of 10"
)

# Test case 14: Multiplication with very small numbers
var a14 = Decimal("0." + "0" * 25 + "1")
var b14 = Decimal("0." + "0" * 25 + "1")
var result14 = a14 * b14
testing.assert_equal(
String(result14),
"0." + "0" * 28,
"Multiplication of very small numbers",
)

# Test case 15: Verify that a * 0 = 0 for various values - individual test cases
var zero = Decimal("0")

# Test 15a: Multiplication of zero by zero
var value15a = Decimal("0")
testing.assert_equal(
String(value15a * zero),
"0",
"Multiplication by zero should yield zero (zero case)",
)

# Test 15b: Multiplication of positive number by zero
var value15b = Decimal("123.45")
testing.assert_equal(
String(value15b * zero),
"0.00",
"Multiplication by zero should yield zero (positive number case)",
)

# Test 15c: Multiplication of negative number by zero
var value15c = Decimal("-987.654")
testing.assert_equal(
String(value15c * zero),
"0.000",
"Multiplication by zero should yield zero (negative number case)",
)

# Test 15d: Multiplication of small number by zero
var value15d = Decimal("0.0001")
testing.assert_equal(
String(value15d * zero),
"0.0000",
"Multiplication by zero should yield zero (small number case)",
)

# Test 15e: Multiplication of large negative number by zero
var value15e = Decimal("-99999.99999")
testing.assert_equal(
String(value15e * zero),
"0.00000",
"Multiplication by zero should yield zero (large negative number case)",
)

print("Decimal multiplication tests passed!")


fn test_power_integer_exponents() raises:
print("------------------------------------------------------")
print("Testing power with integer exponents...")
Expand Down Expand Up @@ -894,9 +725,6 @@ fn main() raises:
# Run subtraction tests
test_subtract()

# Run multiplication tests
test_multiplication()

# Run power tests with integer exponents
test_power_integer_exponents()

Expand Down
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