feat: add ledger.debtRatio()

Author: wraithgar

src/decision-engine/ledger.js

@@ -39,6 +39,10 @@ class Ledger {
   wantlistContains (cid) {
     return this.wantlist.contains(cid)
   }
+
+  debtRatio () {
+    return (this.accounting.bytesSent / (this.accounting.bytesRecv + 1)) // +1 is to prevent division by zero
+  }
 }
 
 module.exports = Ledger

test/decision-engine/ledger.spec.js

@@ -38,5 +38,7 @@ describe('Ledger', () => {
         bytesSent: 100 + 12000,
         bytesRecv: 223432 + 2333
       })
+    expect(ledger.debtRatio())
+      .to.eql((100 + 12000) / (223432 + 2333 + 1))
   })
 })