j129: add entry-point check for the virtual-bullet overlay draw proc

ModularBot_garage/tests/test_vbullet_draw.nim

@@ -143,6 +143,20 @@ proc testEmit() =
   check "SVG carries the aim circles and the legend",
         svg.count("<circle") == 4 and "<text" in svg
 
+proc testEntryPoint() =
+  ## The exact proc `ModularBot.run` calls when TR_VBULLET_DEBUG is on.
+  clearGraphics()
+  var t = makeTracker()
+  let resolved = @[VbResolved(gunId: 1, aimX: AimX, aimY: AimY,
+                              actualX: AimX + 25.0, actualY: AimY, hit: false)]
+  let n = drawVirtualBullets(t, resolved, 1, VbFilterSelected, 100,
+                             ["HeadOn", "Linear", "Pattern"])
+  let svg = svgOutput()
+  check "entry point: 4 active bullets (8 prims) + 1 resolved (2 prims): " & $n,
+        n == 10
+  check "entry point emits 4 path lines + 1 miss line and a legend",
+        svg.count("<line") == 5 and svg.count("<circle") == 5 and "<text" in svg
+
 proc testColours() =
   check "gun 5 (Pattern) turret is green", gunTurretColor(5) == "#00CC44"
   check "gun 0 (HeadOn) turret is white", gunTurretColor(0) == "#FFFFFF"
@@ -164,6 +178,7 @@ testFilter()
 testCap()
 testResolved()
 testEmit()
+testEntryPoint()
 testColours()
 
 if failures > 0: