Added getnCenturyValue with tests

lib/DayCalculator.dart

@@ -49,4 +49,33 @@ class DayCalculator {
       }
     }
   }
+
+  static int getCenturyValue(int year){
+    // Returns the century code for the year
+    // TODO: Implement Julian calendar?
+    year = (year / 100).floor() * 100;
+    switch(year){
+      case 1700:{
+        return 4;
+      }
+      case 1800:{
+        return 2;
+      }
+      case 1900:{
+        return 0;
+      }
+      case 2000:{
+        return 6;
+      }
+      case 2100:{
+        return 4;
+      }
+      case 2200:{
+        return 2;
+      }
+      default:{ //2300
+        return 0;
+      }
+    }
+  }
 }

test/widget_test.dart

@@ -54,4 +54,83 @@ void main() {
       expect(DayCalculator.getMonthValue(11), equals(5));
     });
   });
+  group("DayCalculator getCenturyValue()", () {
+    group("1700s", () {
+      test("1700", (){
+        expect(DayCalculator.getCenturyValue(1700), equals(4));
+      });
+      test("1799", (){
+        expect(DayCalculator.getCenturyValue(1799), equals(4));
+      });
+      test("1777", (){
+        expect(DayCalculator.getCenturyValue(1777), equals(4));
+      });
+    });
+    group("1800s", () {
+      test("1800", (){
+        expect(DayCalculator.getCenturyValue(1800), equals(2));
+      });
+      test("1899", (){
+        expect(DayCalculator.getCenturyValue(1899), equals(2));
+      });
+      test("1843", (){
+        expect(DayCalculator.getCenturyValue(1843), equals(2));
+      });
+    });
+    group("1900s", () {
+      test("1900", (){
+        expect(DayCalculator.getCenturyValue(1900), equals(0));
+      });
+      test("1999", (){
+        expect(DayCalculator.getCenturyValue(1999), equals(0));
+      });
+      test("1938", (){
+        expect(DayCalculator.getCenturyValue(1943), equals(0));
+      });
+    });
+    group("2000s", () {
+      test("2000", (){
+        expect(DayCalculator.getCenturyValue(2000), equals(6));
+      });
+      test("2099", (){
+        expect(DayCalculator.getCenturyValue(2099), equals(6));
+      });
+      test("2064", (){
+        expect(DayCalculator.getCenturyValue(2064), equals(6));
+      });
+    });
+    group("2100s", () {
+      test("2100", (){
+        expect(DayCalculator.getCenturyValue(2100), equals(4));
+      });
+      test("2199", (){
+        expect(DayCalculator.getCenturyValue(2199), equals(4));
+      });
+      test("2158", (){
+        expect(DayCalculator.getCenturyValue(2158), equals(4));
+      });
+    });
+    group("2200s", () {
+      test("2200", (){
+        expect(DayCalculator.getCenturyValue(2200), equals(2));
+      });
+      test("2299", (){
+        expect(DayCalculator.getCenturyValue(2299), equals(2));
+      });
+      test("2249", (){
+        expect(DayCalculator.getCenturyValue(2249), equals(2));
+      });
+    });
+    group("2300s", () {
+      test("2300", (){
+        expect(DayCalculator.getCenturyValue(2300), equals(0));
+      });
+      test("2399", (){
+        expect(DayCalculator.getCenturyValue(2399), equals(0));
+      });
+      test("2304", (){
+        expect(DayCalculator.getCenturyValue(23049), equals(0));
+      });
+    });
+  });
 }