Make sure cost is shown even when equaling 0

Fixes #634

src/components/PlanNodeDetail.vue

@@ -294,7 +294,7 @@ watch(activeTab, () => {
           }"
         ></FontAwesomeIcon>
       </div>
-      <div v-if="node[NodeProp.EXCLUSIVE_COST]">
+      <div v-if="!_.isUndefined(node[NodeProp.EXCLUSIVE_COST])">
         <FontAwesomeIcon
           fixed-width
           :icon="faDollarSign"

src/services/__tests__/17-cost-0.00.spec.ts

@@ -0,0 +1,16 @@
+import { PlanService } from "@/services/plan-service"
+import type { IPlan, IPlanContent } from "@/interfaces"
+
+describe("PlanService", () => {
+  test("Computes exclusive cost correctly", () => {
+    const planService = new PlanService()
+
+    // tslint:disable:max-line-length
+    const source = `Seq Scan on atividade_economica ae  (cost=0.00..0.00 rows=1 width=36)`
+
+    const r = planService.fromSource(source) as IPlanContent
+    const plan: IPlan = planService.createPlan("", r, "")
+    const root = plan.content.Plan
+    root && expect(root["*Cost (exclusive)"]).toBe(0)
+  })
+})

src/services/plan-service.ts

@@ -233,7 +233,7 @@ export class PlanService {
       node[NodeProp.EXCLUSIVE_DURATION] = duration > 0 ? duration : 0
     }
 
-    if (node[NodeProp.TOTAL_COST]) {
+    if (!_.isUndefined(node[NodeProp.TOTAL_COST])) {
       node[NodeProp.EXCLUSIVE_COST] = node[NodeProp.TOTAL_COST]
     }