fix(runtime_metrics): fix non-native runtime.node.heap tags (#7628)

The fallback when the runtime metrics is not using the native
module would send the wrong tags. This happens more frequent due
to having optional dependencies now.

Fixes: #7555

Author: BridgeAR

packages/dd-trace/src/runtime_metrics/runtime_metrics.js

@@ -238,7 +238,7 @@ function captureHeapSpace () {
   const stats = v8.getHeapSpaceStatistics()
 
   for (let i = 0, l = stats.length; i < l; i++) {
-    const tags = [`space:${stats[i].space_name}`]
+    const tags = [`heap_space:${stats[i].space_name}`]
 
     client.gauge('runtime.node.heap.size.by.space', stats[i].space_size, tags)
     client.gauge('runtime.node.heap.used_size.by.space', stats[i].space_used_size, tags)

packages/dd-trace/test/runtime_metrics.spec.js

@@ -292,6 +292,9 @@ function createGarbage (count = 50) {
           const isGC95Percentile = sinon.match((value) => {
             return value >= 1e5 && value < 1e8 // In Nanoseconds. 0.1ms to 100ms.
           })
+          const isHeapSpace = sinon.match((metricName) => {
+            return /^heap_space:[a-z_]+$/.test(metricName)
+          })
 
           // These return percentages as strings and are tested later.
           sinon.assert.calledWith(client.gauge, 'runtime.node.cpu.user')
@@ -349,10 +352,15 @@ function createGarbage (count = 50) {
             })
           )
 
-          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.size.by.space', isFiniteNumber)
-          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.used_size.by.space', isFiniteNumber)
-          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.available_size.by.space', isFiniteNumber)
-          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.physical_size.by.space', isFiniteNumber)
+          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.size.by.space', isFiniteNumber, isHeapSpace)
+          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.used_size.by.space', isFiniteNumber, isHeapSpace)
+          sinon.assert.calledWith(
+            client.gauge,
+            'runtime.node.heap.available_size.by.space',
+            isFiniteNumber,
+            isHeapSpace
+          )
+          sinon.assert.calledWith(client.gauge, 'runtime.node.heap.physical_size.by.space', isFiniteNumber, isHeapSpace)
 
           sinon.assert.called(client.flush)
         })