feat: Calculate age class interval dynamically from given yield table

src/utils/getAgeClassInterval.test.ts

@@ -0,0 +1,16 @@
+import yieldTables from '../constants/yieldTables';
+import getAgeClassInterval from './getAgeClassInterval';
+
+describe('The getAgeClassInterval forest util', () => {
+  it('should return the age class interval for a yield table', () => {
+    const result = getAgeClassInterval(yieldTables['at_tirol_laercheSuedtirol']);
+
+    expect(result).toEqual(10);
+  });
+
+  it('should return the age class interval for a yield table', () => {
+    const result = getAgeClassInterval(yieldTables['de_assmann_fichteBayernOcell']);
+
+    expect(result).toEqual(5);
+  });
+});

src/utils/getAgeClassInterval.ts

@@ -0,0 +1,8 @@
+import YieldTable from '../models/YieldTable';
+
+const getAgeClassInterval = (yieldTable: YieldTable): number => {
+  const ageClassInterval = yieldTable.rows[1].age - yieldTable.rows[0].age;
+  return ageClassInterval;
+};
+
+export default getAgeClassInterval;

src/utils/getNormalStock.test.ts

@@ -40,6 +40,20 @@ describe('The getNormalStock forest util', () => {
     expect(actual.toFixed(0)).toEqual(expected);
   });
 
+  it('should return the normal stock for a yield class', () => {
+    const yieldClass = 3.7;
+    const rotationPeriod = 85;
+    const expected = '171';
+
+    const actual = getNormalStock(
+      yieldTables['de_assmann_fichteBayernOcell'],
+      yieldClass,
+      rotationPeriod
+    );
+
+    expect(actual.toFixed(0)).toEqual(expected);
+  });
+
   it('throws an error if no age level is found in the given yield table for the given rotation period', () => {
     const yieldClass = 7.1;
     const rotationPeriod = 135;

src/utils/getNormalStock.ts

@@ -1,4 +1,5 @@
 import YieldTable, { YieldTableRow } from '../models/YieldTable';
+import getAgeClassInterval from './getAgeClassInterval';
 import getYieldClasses from './getYieldClasses';
 
 const getNormalStock = (
@@ -18,8 +19,8 @@ const getNormalStock = (
   // Get the yield classes via the `getYieldClasses` util (The util returns one or two yield classes)
   const yieldClasses: number[] = getYieldClasses(yieldTable, siteProductivity);
 
-  // Define the age gap
-  const ageGap: number = 10; // TODO: get dynamically from yield table via a new forest util
+  // Get the age class interval
+  const ageClassInterval = getAgeClassInterval(yieldTable);
 
   // Get the yield table rows for the relevant yield classes and relevant age levels
   const yieldTableRowsForRelevantYieldClassesAndAgeLevels: YieldTableRow[][] = yieldClasses.map(
@@ -40,7 +41,7 @@ const getNormalStock = (
         return acc + stock;
       }, 0);
 
-      return (ageGap / rotationPeriod) * sumOfStocks;
+      return (ageClassInterval / rotationPeriod) * sumOfStocks;
     }
   );