fix: places should be optional for $trunc and $round (#368)

* fix: updated truncate function to default to 0 places

Updated truncate function to default to 0 places as per mongo documentation.

https://www.mongodb.com/docs/manual/reference/operator/aggregation/trunc/

* test: added optional places unit tests for $round and $trunc

src/operators/expression/arithmetic/_internal.ts

@@ -6,8 +6,8 @@
  */
 export function truncate(
   num: number,
-  places: number,
-  roundOff: boolean
+  places: number = 0,
+  roundOff: boolean = false
 ): number {
   const sign = Math.abs(num) === num ? 1 : -1;
   num = Math.abs(num);

test/operators/expression/arithmetic.test.ts

@@ -95,6 +95,15 @@ support.runTest("operators/expression/arithmetic", {
     [[34.32, -1], 30],
     [[-45.39, -1], -50],
     // rounded to the whole integer
+    [[19.25], 19],
+    [[28.73], 29],
+    [[34.32], 34],
+    [[-45.39], -45],
+    [[10.4], 10],
+    [[10.6], 11],
+    [[10.7], 11],
+    [[11.4], 11],
+    [[11.9], 12],
     [[19.25, 0], 19],
     [[28.73, 0], 29],
     [[34.32, 0], 34],
@@ -137,6 +146,10 @@ support.runTest("operators/expression/arithmetic", {
     [[34.32, -1], 30],
     [[-45.39, -1], -40],
     // truncate to the whole integer
+    [[19.25], 19],
+    [[28.73], 28],
+    [[34.32], 34],
+    [[-45.39], -45],
     [[19.25, 0], 19],
     [[28.73, 0], 28],
     [[34.32, 0], 34],