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f91bd05 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 | """Tests for fire_math.py — core FIRE calculation logic."""
import pytest
from fire_math import calculate_fire, calculate_years_to_fi, calculate_scenario, projection_timeline
# ---------------------------------------------------------------------------
# calculate_fire — Core Metrics
# ---------------------------------------------------------------------------
def test_basic_case():
result = calculate_fire(
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1998,
)
assert result.fi_number == 600000.0
assert result.savings_rate == 50.0
assert result.monthly_savings == 2000.0
def test_already_fi():
# Portfolio exceeds FI number — years_to_fi must be 0.0, NOT None.
# This tests the line-68 bug fix: `if years_to_fi is not None` instead of `if years_to_fi`.
result = calculate_fire(
monthly_income=2000,
monthly_expenses=2000,
total_portfolio=700000,
birth_year=1998,
)
assert result.years_to_fi == 0.0, (
"years_to_fi must be 0.0 when already FI, not None. "
"Check the line-68 bug fix."
)
assert result.fi_date is not None
def test_zero_income():
result = calculate_fire(
monthly_income=0,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1998,
)
assert result.savings_rate == 0
def test_never_fi():
# Zero savings + zero portfolio → compound growth on 0 stays 0 → never reaches target.
result = calculate_fire(
monthly_income=2000,
monthly_expenses=2000,
total_portfolio=0,
birth_year=1998,
)
assert result.monthly_savings == 0.0
assert result.years_to_fi is None
assert result.fi_date is None
# ---------------------------------------------------------------------------
# calculate_years_to_fi — Iteration Logic
# ---------------------------------------------------------------------------
def test_already_at_target():
result = calculate_years_to_fi(
current_portfolio=600000,
annual_savings=24000,
target=600000,
annual_return=0.05,
)
assert result == 0.0
def test_normal_projection():
result = calculate_years_to_fi(
current_portfolio=50000,
annual_savings=24000,
target=600000,
annual_return=0.05,
)
assert result is not None
assert 13 <= result <= 20, f"Expected 13–20 years, got {result}"
def test_no_savings_no_return():
result = calculate_years_to_fi(
current_portfolio=50000,
annual_savings=0,
target=600000,
annual_return=0,
)
assert result is None
def test_max_years_cap():
# Savings so tiny the loop hits the 100-year cap.
result = calculate_years_to_fi(
current_portfolio=0,
annual_savings=12, # €1/month
target=10_000_000,
annual_return=0,
)
assert result is None
# ---------------------------------------------------------------------------
# projection_timeline — Chart Data
# ---------------------------------------------------------------------------
def test_timeline_length():
timeline = projection_timeline(
total_portfolio=50000,
monthly_savings=2000,
annual_return=0.05,
years=30,
)
assert len(timeline) == 31 # year 0 through year 30 inclusive
def test_first_entry():
starting = 75000.0
timeline = projection_timeline(
total_portfolio=starting,
monthly_savings=1500,
annual_return=0.05,
years=20,
)
assert timeline[0]["portfolio"] == starting
def test_growth():
timeline = projection_timeline(
total_portfolio=10000,
monthly_savings=500,
annual_return=0.05,
years=10,
)
for i in range(1, len(timeline)):
assert timeline[i]["portfolio"] > timeline[i - 1]["portfolio"]
# ---------------------------------------------------------------------------
# calculate_scenario — What-If
# ---------------------------------------------------------------------------
def test_extra_savings():
base = calculate_fire(
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1990,
)
scenario = calculate_scenario(
base=base,
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1990,
extra_monthly_savings=500,
)
assert scenario.years_to_fi is not None
assert base.years_to_fi is not None
assert scenario.years_to_fi < base.years_to_fi
def test_lower_expenses():
base = calculate_fire(
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1990,
)
scenario = calculate_scenario(
base=base,
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1990,
adjusted_expenses=1500,
)
assert scenario.fi_number < base.fi_number
# ---------------------------------------------------------------------------
# fi_date — Edge Cases for Month/Year Boundary Arithmetic
# ---------------------------------------------------------------------------
def test_fi_date_zero_years_to_fi():
"""When already FI (years_to_fi=0.0), fi_date must be first of current month."""
from datetime import date
result = calculate_fire(
monthly_income=2000,
monthly_expenses=2000,
total_portfolio=700000,
birth_year=1998,
)
assert result.fi_date is not None
assert result.fi_date.day == 1
assert result.fi_date.year == date.today().year
assert result.fi_date.month == date.today().month
def test_fi_date_whole_years():
"""Fractional part = 0.0 — fi_date must land in the current month of a future year."""
from datetime import date
# Force years_to_fi to be a whole number by giving a result we can verify.
# We use calculate_years_to_fi directly to avoid dependency on date.today() internals.
from fire_math import calculate_years_to_fi
result = calculate_years_to_fi(
current_portfolio=0,
annual_savings=60000,
target=600000,
annual_return=0.0, # No compounding — pure savings: exactly 10 years
)
assert result is not None
# 10 years of €60k/year = €600k exactly — should be ~10 years
assert 9.9 <= result <= 10.1
def test_fi_date_fractional_month_no_overflow():
"""Adding fractional months must not produce month > 12 for any start month."""
from datetime import date
from unittest.mock import patch
for start_month in range(1, 13):
fake_today = date(2026, start_month, 15)
with patch("fire_math.date") as mock_date:
mock_date.today.return_value = fake_today
mock_date.side_effect = lambda *args, **kw: date(*args, **kw)
result = calculate_fire(
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1998,
)
if result.fi_date is not None:
assert 1 <= result.fi_date.month <= 12, (
f"fi_date.month={result.fi_date.month} out of range for start_month={start_month}"
)
assert result.fi_date.year >= 2026
def test_fi_date_december_wrap():
"""December + 9 fractional months = September of next year. Must not add extra year."""
from datetime import date
from unittest.mock import patch
# Simulate running in December with 15.75 years to FI
# Dec (12) + 9 fractional months = 21 → extra_years=1, final_month=9
# Expected: year=2026+15+1=2042, month=9
fake_today = date(2026, 12, 1)
with patch("fire_math.date") as mock_date:
mock_date.today.return_value = fake_today
mock_date.side_effect = lambda *args, **kw: date(*args, **kw)
result = calculate_fire(
monthly_income=4000,
monthly_expenses=2000,
total_portfolio=50000,
birth_year=1998,
)
if result.fi_date is not None:
# fi_date must be a valid date
assert 1 <= result.fi_date.month <= 12
assert result.fi_date.year > 2026
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