Add external row quantity foundation

tests/circuit-device-row-quantity.test.ts

@@ -0,0 +1,62 @@
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import { describe, it } from "node:test";
+import Database from "better-sqlite3";
+import {
+  assertCircuitDeviceRowQuantity,
+  calculateCircuitDeviceRowQuantity,
+} from "../src/domain/calculations/circuit-device-row-quantity.js";
+
+describe("circuit device-row quantity", () => {
+  it("adds the manual share and every indivisible external quantity", () => {
+    assert.equal(
+      calculateCircuitDeviceRowQuantity(2, [
+        { effectiveQuantity: 2 },
+        { effectiveQuantity: 1 },
+      ]),
+      5
+    );
+    assert.doesNotThrow(() => assertCircuitDeviceRowQuantity({
+      quantity: 5,
+      manualQuantity: 2,
+      externalObjects: [{ effectiveQuantity: 2 }, { effectiveQuantity: 1 }],
+    }));
+  });
+
+  it("rejects invalid shares and a stale materialized total", () => {
+    assert.throws(
+      () => calculateCircuitDeviceRowQuantity(-1, []),
+      /Manual quantity/
+    );
+    assert.throws(
+      () => calculateCircuitDeviceRowQuantity(0, [{ effectiveQuantity: 0 }]),
+      /External effective quantity/
+    );
+    assert.throws(
+      () => assertCircuitDeviceRowQuantity({
+        quantity: 2,
+        manualQuantity: 1,
+        externalObjects: [{ effectiveQuantity: 2 }],
+      }),
+      /does not match/
+    );
+  });
+
+  it("preserves existing row quantities in migration 0005", () => {
+    const database = new Database(":memory:");
+    try {
+      database.exec("CREATE TABLE circuit_device_rows (id text PRIMARY KEY, quantity integer NOT NULL)");
+      database.exec("INSERT INTO circuit_device_rows (id, quantity) VALUES ('row-1', 7)");
+      const migration = fs
+        .readFileSync("src/db/migrations/0005_stale_gorilla_man.sql", "utf8")
+        .replaceAll("--> statement-breakpoint", "");
+      database.exec(migration);
+      assert.deepEqual(
+        database.prepare("SELECT quantity, manual_quantity FROM circuit_device_rows").get(),
+        { quantity: 7, manual_quantity: 7 }
+      );
+    } finally {
+      database.close();
+    }
+  });
+});