fix(hubs): Fix Data Explorer dashboard savings formulas and exclude commitment purchases

docs-mslearn/toolkit/changelog.md

@@ -3,7 +3,7 @@ title: FinOps toolkit changelog
 description: Review the latest features and enhancements in the FinOps toolkit, including updates to FinOps hubs, Power BI reports, and more.
 author: MSBrett
 ms.author: brettwil
-ms.date: 10/28/2026
+ms.date: 10/29/2026
 ms.topic: reference
 ms.service: finops
 ms.subservice: finops-toolkit
@@ -18,14 +18,17 @@ ms.reviewer: brettwil
 
 This article summarizes the features and enhancements in each release of the FinOps toolkit.
 
-<!--
 <br>
 
 ## Unreleased
 
 The following section lists features and enhancements that are currently in development.
 
--->
+### [FinOps hubs](hubs/finops-hubs-overview.md) v16
+
+- **Changed**
+  - Changed the Data Explorer dashboard's Cost summary, Savings summary, Savings breakdown by month, savings pie and trend, stacked cost + savings, and Effective Savings Rate tiles to derive their displayed List cost and Contracted cost operands from the same clamped, row-level savings basis as the results shown alongside them, so the on-screen equations (for example, "List − Contracted = Negotiated savings") always reconcile. This changes the Effective Savings Rate definition on the affected tiles from `(sum(ListCost) − sum(EffectiveCost)) / sum(ListCost)` to a derived List cost built from Effective cost plus the clamped Negotiated and Commitment savings sums. Total savings is now the sum of the clamped Negotiated and Commitment savings everywhere it is shown, commitment discount purchases are excluded from savings on every Summary and Rate optimization tile using the same `x_AmortizationClass != 'Principal'` filter, and the Effective Savings Rate shows blank instead of NaN when List cost is 0 ([#2093](https://github.com/microsoft/finops-toolkit/issues/2093)).
+
 
 <br><a name="latest"></a>
 

src/powershell/Tests/Unit/HubsDashboardSavings.Tests.ps1

@@ -0,0 +1,50 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+<#
+    Regression coverage for Data Explorer dashboard savings formulas (#2093 / PR #2248):
+
+    1. Savings are never computed by subtracting raw aggregates (sum(ListCost) - sum(EffectiveCost)); tiles use the
+       row-level clamped x_*Savings columns so every displayed operand and result share one basis.
+    2. Commitment purchases are excluded via x_AmortizationClass != 'Principal'; the older
+       ChargeCategory == 'Usage' or isempty(CommitmentDiscountId) variant is gone.
+    3. Every Effective Savings Rate guards against a zero List cost (blank instead of NaN).
+#>
+
+Describe 'HubsDashboardSavings' {
+
+    BeforeDiscovery {
+        $repoRoot = (Resolve-Path "$PSScriptRoot/../../../..").Path
+        $dashboard = Get-Content (Join-Path $repoRoot 'src/templates/finops-hub/dashboard.json') -Raw | ConvertFrom-Json
+        $queries = @($dashboard.queries | ForEach-Object { @{ Id = $_.id.Substring(0, 8); Text = [string]$_.text } })
+        # 3886b5cd pivots Effective cost only; its savings columns are never displayed.
+        $savingsQueries = @($queries | Where-Object { $_.Id -ne '3886b5cd' -and $_.Text -match '(?i)sum(if)?\(\s*x_(Negotiated|Commitment|Total)\w*Savings' })
+    }
+
+    It 'Excludes commitment purchases from all Summary page savings queries' {
+        $summaryQueries = @($queries | Where-Object { $_.Text -match "(?i)sumif\(\s*x_(Negotiated|Commitment)DiscountSavings\s*,\s*x_AmortizationClass\s*!=\s*'Principal'\s*\)" })
+        $summaryQueries.Count | Should -BeGreaterOrEqual 9
+    }
+
+    Context 'Query <Id>' -ForEach $queries {
+        It 'Does not subtract raw aggregates to compute savings' {
+            $Text | Should -Not -Match '(?i)sum\(\s*(List|Contracted)Cost\s*\)\s*-\s*sum\('
+        }
+
+        It 'Does not use the legacy commitment purchase filter' {
+            $Text | Should -Not -Match "(?i)ChargeCategory\s*==\s*'Usage'\s+or\s+isempty\(CommitmentDiscountId\)"
+        }
+    }
+
+    Context 'Savings query <Id>' -ForEach $savingsQueries {
+        It 'Excludes commitment purchases or is limited to usage rows' {
+            $Text | Should -Match "(?i)x_AmortizationClass\s*!=\s*'Principal'|ChargeCategory\s*==\s*'Usage'"
+        }
+
+        It 'Guards the savings rate against zero list cost' {
+            if ($Text -match '(?i)EffectiveSavingsRate\s*=') {
+                $Text | Should -Match '(?i)ListCost\s*==\s*0'
+            }
+        }
+    }
+}