Fix problem with check target numbers <= 0

The fix has 2 components:
1. The logic for evaluating checks now supports check target numbers<= 0
   by still using a single die in this case
2.  The CheckFactory sets the check target number to 0 even if it would
   be < 0. This is necessary because negative numbers would interfer
   with foundry's math evaluation in rolls and would not be picked up
   correctly.

spec/rolls/check-evaluation.spec.ts

@@ -48,30 +48,134 @@ describe("evaluateCheck with a single die", () => {
             { result: 20, checkTargetNumber: 4, active: false, discarded: true, failure: true },
         ]);
     });
+
+    it("should roll a die even when the checkTargetNumber is 0 and coup on 1", () => {
+        expect(evaluateCheck([1], 0)).toEqual([
+            { result: 1, checkTargetNumber: 0, active: true, discarded: false, success: true, count: 0 },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is 0 and fail on values > 1 and < 20", () => {
+        for (let i = 2; i < 20; i++) {
+            expect(evaluateCheck([i], 0)).toEqual([
+                { result: i, checkTargetNumber: 0, active: false, discarded: true },
+            ]);
+        }
+    });
+
+    it("should roll a die even when the checkTargetNumber is 0 and fumble on 20", () => {
+        expect(evaluateCheck([20], 0)).toEqual([
+            { result: 20, checkTargetNumber: 0, active: false, discarded: true, failure: true },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is < 0 and coup on 1", () => {
+        expect(evaluateCheck([1], -1)).toEqual([
+            { result: 1, checkTargetNumber: -1, active: true, discarded: false, success: true, count: -1 },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is < 0 and fail on values > 1 and < 20", () => {
+        for (let i = 2; i < 20; i++) {
+            expect(evaluateCheck([i], -1)).toEqual([
+                { result: i, checkTargetNumber: -1, active: false, discarded: true },
+            ]);
+        }
+    });
+
+    it("should roll a die even when the checkTargetNumber is < 0 and fumble on 20", () => {
+        expect(evaluateCheck([20], -1)).toEqual([
+            { result: 20, checkTargetNumber: -1, active: false, discarded: true, failure: true },
+        ]);
+    });
 });
 
 describe("evaluateCheck with a single die and coup / fumble modification", () => {
+    const maximumCoupResult = 2;
+    const minimumFumbleResult = 19;
+
     it("should assign the checkTargetNumber to the single die and coup on 'maximumCoupResult'", () => {
-        expect(evaluateCheck([2], 4, { maximumCoupResult: 2 })).toEqual([
+        expect(evaluateCheck([maximumCoupResult], 4, { maximumCoupResult })).toEqual([
-            { result: 2, checkTargetNumber: 4, active: true, discarded: false, success: true, count: 4 },
+            {
+                result: maximumCoupResult,
+                checkTargetNumber: 4,
+                active: true,
+                discarded: false,
+                success: true,
+                count: 4,
+            },
         ]);
     });
 
-    it("should assign the checkTargetNumber to the single die and not coup on lower edge case '3'", () => {
+    it("should assign the checkTargetNumber to the single die and not coup on lower edge case 'maximumCoupResult + 1'", () => {
-        expect(evaluateCheck([3], 4, { maximumCoupResult: 2 })).toEqual([
+        expect(evaluateCheck([maximumCoupResult + 1], 4, { maximumCoupResult })).toEqual([
-            { result: 3, checkTargetNumber: 4, active: true, discarded: false },
+            { result: maximumCoupResult + 1, checkTargetNumber: 4, active: true, discarded: false },
         ]);
     });
 
-    it("should assign the checkTargetNumber to the single die and fumble on 'minimumFUmbleResultResult'", () => {
+    it("should assign the checkTargetNumber to the single die and fumble on 'minimumFumbleResultResult'", () => {
-        expect(evaluateCheck([19], 20, { minimumFumbleResult: 19 })).toEqual([
+        expect(evaluateCheck([minimumFumbleResult], 20, { minimumFumbleResult })).toEqual([
-            { result: 19, checkTargetNumber: 20, active: true, discarded: false, failure: true },
+            { result: minimumFumbleResult, checkTargetNumber: 20, active: true, discarded: false, failure: true },
         ]);
     });
 
-    it("should assign the checkTargetNumber to the single die and not fumble on upper edge case '18'", () => {
+    it("should assign the checkTargetNumber to the single die and not fumble on upper edge case 'minimumFumbleResult - 1'", () => {
-        expect(evaluateCheck([18], 20, { minimumFumbleResult: 19 })).toEqual([
+        expect(evaluateCheck([minimumFumbleResult - 1], 20, { minimumFumbleResult })).toEqual([
-            { result: 18, checkTargetNumber: 20, active: true, discarded: false },
+            { result: minimumFumbleResult - 1, checkTargetNumber: 20, active: true, discarded: false },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is 0 and coup on 'maximumCoupResult'", () => {
+        expect(evaluateCheck([maximumCoupResult], 0, { maximumCoupResult })).toEqual([
+            {
+                result: maximumCoupResult,
+                checkTargetNumber: 0,
+                active: true,
+                discarded: false,
+                success: true,
+                count: 0,
+            },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is 0 and fail on '> maximumCoupResult and < minimumFumbleResult", () => {
+        for (let i = maximumCoupResult + 1; i < minimumFumbleResult; i++) {
+            expect(evaluateCheck([i], 0, { maximumCoupResult, minimumFumbleResult })).toEqual([
+                { result: i, checkTargetNumber: 0, active: false, discarded: true },
+            ]);
+        }
+    });
+
+    it("should roll a die even when the checkTargetNumber is 0 and fumble on 'minimumFumbleResult'", () => {
+        expect(evaluateCheck([minimumFumbleResult], 0, { minimumFumbleResult })).toEqual([
+            { result: minimumFumbleResult, checkTargetNumber: 0, active: false, discarded: true, failure: true },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is < 0 and coup on 'maximumCoupResult'", () => {
+        expect(evaluateCheck([maximumCoupResult], -1, { maximumCoupResult })).toEqual([
+            {
+                result: maximumCoupResult,
+                checkTargetNumber: -1,
+                active: true,
+                discarded: false,
+                success: true,
+                count: -1,
+            },
+        ]);
+    });
+
+    it("should roll a die even when the checkTargetNumber is < 0 and fail on '> maximumCoupResult and < minimumFumbleResult", () => {
+        for (let i = maximumCoupResult + 1; i < minimumFumbleResult; i++) {
+            expect(evaluateCheck([i], -1, { maximumCoupResult, minimumFumbleResult })).toEqual([
+                { result: i, checkTargetNumber: -1, active: false, discarded: true },
+            ]);
+        }
+    });
+
+    it("should roll a die even when the checkTargetNumber is < 0 and fumble on 'minimumFumbleResult'", () => {
+        expect(evaluateCheck([minimumFumbleResult], -1, { minimumFumbleResult })).toEqual([
+            { result: minimumFumbleResult, checkTargetNumber: -1, active: false, discarded: true, failure: true },
         ]);
     });
 });

src/module/rolls/check-evaluation.ts

@@ -113,5 +113,5 @@ function evaluateDiceWithSubChecks(
 }
 
 export function getRequiredNumberOfDice(checkTargetNumber: number): number {
-    return Math.ceil(checkTargetNumber / 20);
+    return Math.max(Math.ceil(checkTargetNumber / 20), 1);
 }

src/module/rolls/check-factory.ts

@@ -45,8 +45,8 @@ class CheckFactory {
         );
     }
 
-    createCheckTargetNumberModifier(): string | null {
+    createCheckTargetNumberModifier(): string {
-        return "v" + (this.checkTargetNumber + this.gmModifier);
+        return "v" + Math.max(this.checkTargetNumber + this.gmModifier, 0);
     }
 
     createCoupFumbleModifier(): string | null {