Log the number of dependency snapshots installed and how many snapshots to keep (#605)

* Log the number of dependency snapshots installed and how many we should keep

* Add test case to validate log statement for dependency snapshots installed and snapshots to keep

Author: Francisco-Gamino

src/DependencyManagement/DependencySnapshotPurger.cs

@@ -73,6 +73,12 @@ public void Purge(ILogger logger)
                                             .OrderBy(entry => entry.Item2)
                                             .ToArray();
 
+            var snapshotsLogmessage = string.Format(
+                                        PowerShellWorkerStrings.LogDependencySnapshotsInstalledAndSnapshotsToKeep,
+                                        pathSortedByAccessTime.Length,
+                                        _minNumberOfSnapshotsToKeep);
+            logger.Log(isUserOnlyLog: false, LogLevel.Trace, snapshotsLogmessage);
+
             for (var i = 0; i < pathSortedByAccessTime.Length - _minNumberOfSnapshotsToKeep; ++i)
             {
                 var creationTime = pathSortedByAccessTime[i].Item2;

src/resources/PowerShellWorkerStrings.resx

@@ -334,4 +334,7 @@
   <data name="SettingCurrentDirectory" xml:space="preserve">
     <value>Setting current directory to '{0}'.</value>
   </data>
+  <data name="LogDependencySnapshotsInstalledAndSnapshotsToKeep" xml:space="preserve">
+    <value>Number of dependency snapshots installed: '{0}'. Dependency snapshots to keep: '{1}'.</value>
+  </data>
 </root>

test/Unit/DependencyManagement/DependencySnapshotPurgerTests.cs

@@ -319,5 +319,36 @@ public void SetCurrentlyUsedSnapshot_UpdatesCurrentSnapshotAccessTimeImmediately
 
             _mockStorage.Verify(_ => _.SetSnapshotAccessTimeToUtcNow(It.IsAny<string>()), Times.Once);
         }
+
+        [Fact]
+        public void LogDependencySnapshotsInstalledAndSnapshotsToKeep()
+        {
+            var mockLogger = new Mock<ILogger>(MockBehavior.Loose);
+            var mockStorage = new Mock<IDependencyManagerStorage>();
+
+            mockStorage.Setup(_ => _.GetInstalledAndInstallingSnapshots()).Returns(new[] { "1", "2", "3" });
+
+            mockStorage.Setup(_ => _.GetSnapshotAccessTimeUtc("1")).Returns(DateTime.UtcNow - TimeSpan.FromMinutes(11));
+            mockStorage.Setup(_ => _.GetSnapshotAccessTimeUtc("2")).Returns(DateTime.UtcNow);
+            mockStorage.Setup(_ => _.GetSnapshotAccessTimeUtc("3")).Returns(DateTime.UtcNow - TimeSpan.FromMinutes(6));
+
+            using (var purger = new DependencySnapshotPurger(
+                                        mockStorage.Object,
+                                        heartbeatPeriod: TimeSpan.FromMinutes(10),
+                                        oldHeartbeatAgeMargin: TimeSpan.FromMinutes(0),
+                                        minNumberOfSnapshotsToKeep: 1))
+            {
+                purger.Purge(mockLogger.Object);
+            }
+
+            mockLogger.Verify(
+                _ => _.Log(
+                    false,
+                    LogLevel.Trace,
+                    It.Is<string>(
+                        message => message.Contains("Number of dependency snapshots installed: '3'. Dependency snapshots to keep: '1'.")),
+                    null),
+                Times.Once);
+        }
     }
 }