Prune targets not connected to workspace

Sources/DependencyCalculator/DependencyGraph.swift

@@ -153,6 +153,7 @@ extension WorkspaceInfo {
                                           folders: folders,
                                           dependencyStructure: resultDependencies,
                                           candidateTestPlans: candidateTestPlans)
+        let finalWorkspaceInfo: WorkspaceInfo
         if let config {
             let additionalBasePath: Path
             if path.extension == "xcworkspace" || path.extension == "xcodeproj" {
@@ -161,10 +162,14 @@ extension WorkspaceInfo {
                 additionalBasePath = path
             }
             // Process additional config
-            return processAdditional(config: config, workspaceInfo: workspaceInfo, basePath: additionalBasePath)
+            finalWorkspaceInfo = processAdditional(config: config,
+                                                   workspaceInfo: workspaceInfo,
+                                                   basePath: additionalBasePath)
         } else {
-            return workspaceInfo
+            finalWorkspaceInfo = workspaceInfo
         }
+
+        return finalWorkspaceInfo.pruningDisconnectedTargets()
     }
 
     static func processAdditional(config: WorkspaceInfo.AdditionalConfig,

Sources/Workspace/DependencyGraph.swift

@@ -54,4 +54,38 @@ public struct DependencyGraph {
 
         return DependencyGraph(dependsOn: map)
     }
+
+    public func reachableTargets(startingFrom roots: Set<TargetIdentity>) -> Set<TargetIdentity> {
+        guard !roots.isEmpty else { return [] }
+
+        var visited = Set<TargetIdentity>()
+        var stack = Array(roots)
+
+        while let current = stack.popLast() {
+            if visited.contains(current) {
+                continue
+            }
+            visited.insert(current)
+
+            let dependencies = dependsOn[current] ?? Set<TargetIdentity>()
+            for dependency in dependencies where !visited.contains(dependency) {
+                stack.append(dependency)
+            }
+        }
+
+        return visited
+    }
+
+    public func filteringTargets(_ allowed: Set<TargetIdentity>) -> DependencyGraph {
+        guard !allowed.isEmpty else { return DependencyGraph(dependsOn: [:]) }
+
+        var filtered: [TargetIdentity: Set<TargetIdentity>] = [:]
+
+        for target in allowed {
+            let dependencies = (dependsOn[target] ?? Set<TargetIdentity>()).intersection(allowed)
+            filtered[target] = dependencies
+        }
+
+        return DependencyGraph(dependsOn: filtered)
+    }
 }

Sources/Workspace/WorkspaceInfo.swift

@@ -97,3 +97,32 @@ public extension WorkspaceInfo {
         public let dependencies: [String: [String]]
     }
 }
+
+public extension WorkspaceInfo {
+    func pruningDisconnectedTargets() -> WorkspaceInfo {
+        let projectTargets = Set(files.keys.filter { $0.type == .project })
+        guard !projectTargets.isEmpty else { return self }
+
+        var reachable = dependencyStructure.reachableTargets(startingFrom: projectTargets).union(projectTargets)
+        guard !reachable.isEmpty else { return self }
+
+        let reachablePackageRoots = Set(reachable
+            .filter { $0.type == .package }
+            .map { $0.path })
+
+        if !reachablePackageRoots.isEmpty {
+            for target in files.keys where target.type == .package && reachablePackageRoots.contains(target.path) {
+                reachable.insert(target)
+            }
+        }
+
+        let filteredFiles = files.filter { reachable.contains($0.key) }
+        let filteredFolders = folders.filter { reachable.contains($0.value) }
+        let filteredDependencies = dependencyStructure.filteringTargets(reachable)
+
+        return WorkspaceInfo(files: filteredFiles,
+                             folders: filteredFolders,
+                             dependencyStructure: filteredDependencies,
+                             candidateTestPlans: candidateTestPlans)
+    }
+}

Tests/DependencyCalculatorTests/DependencyCalculatorTests.swift

@@ -92,4 +92,67 @@ struct DependencyCalculatorTests {
         // then
         #expect(affected == Set([module, moduleTests, mainApp, mainAppTests]))
     }
+
+    @Test
+    func filtersUnreferencedPackagesWhenWorkspaceHasProjects() throws {
+        let project = TargetIdentity.project(path: Path("/workspace/App.xcodeproj"),
+                                             targetName: "App",
+                                             testTarget: false)
+        let usedPackage = TargetIdentity.package(path: Path("/workspace/Packages/Used"),
+                                                 targetName: "UsedTarget",
+                                                 testTarget: false)
+        let unusedPackage = TargetIdentity.package(path: Path("/workspace/Packages/Unused"),
+                                                   targetName: "UnusedTarget",
+                                                   testTarget: false)
+
+        let files: [TargetIdentity: Set<Path>] = [
+            project: [Path("/workspace/App/App.swift")],
+            usedPackage: [Path("/workspace/Packages/Used/Source.swift")],
+            unusedPackage: [Path("/workspace/Packages/Unused/Source.swift")]
+        ]
+
+        let dependencies = DependencyGraph(dependsOn: [
+            project: Set([usedPackage]),
+            usedPackage: Set()
+        ])
+
+        let info = WorkspaceInfo(files: files,
+                                 folders: [:],
+                                 dependencyStructure: dependencies,
+                                 candidateTestPlan: nil)
+
+        let pruned = info.pruningDisconnectedTargets()
+
+        #expect(pruned.files.keys.contains(project))
+        #expect(pruned.files.keys.contains(usedPackage))
+        #expect(!pruned.files.keys.contains(unusedPackage))
+    }
+
+    @Test
+    func keepsPackagesWhenNoProjectsPresent() throws {
+        let packageA = TargetIdentity.package(path: Path("/workspace/Packages/A"),
+                                              targetName: "ATarget",
+                                              testTarget: false)
+        let packageB = TargetIdentity.package(path: Path("/workspace/Packages/B"),
+                                              targetName: "BTarget",
+                                              testTarget: false)
+
+        let files: [TargetIdentity: Set<Path>] = [
+            packageA: [Path("/workspace/Packages/A/file.swift")],
+            packageB: [Path("/workspace/Packages/B/file.swift")]
+        ]
+
+        let dependencies = DependencyGraph(dependsOn: [
+            packageA: Set([packageB])
+        ])
+
+        let info = WorkspaceInfo(files: files,
+                                 folders: [:],
+                                 dependencyStructure: dependencies,
+                                 candidateTestPlan: nil)
+
+        let pruned = info.pruningDisconnectedTargets()
+
+        #expect(pruned.files.keys == files.keys)
+    }
 }