finance: Add income.py

This is the minimal starting point to model financial income.

2 files changed, 16 insertions, 0 deletions

diff --git a/finance/income.py b/finance/income.py
new file mode 100644
index 0000000..12d5d4e
--- /dev/null
+++ b/finance/income.py
@@ -0,0 +1,10 @@
+import dataclasses
+
+
+@dataclasses.dataclass(kw_only=True, frozen=True)
+class Income:
+
+    amount: float
+
+    def integrate(self, delta_t: int) -> float:
+        return delta_t * self.amount
diff --git a/finance/test_income.py b/finance/test_income.py
new file mode 100644
index 0000000..21d42f7
--- /dev/null
+++ b/finance/test_income.py
@@ -0,0 +1,6 @@
+from finance import income
+
+
+def test_income_integration() -> None:
+    inc = income.Income(amount=3000.0)
+    assert inc.integrate(5) == 15000.0