Permit scheme build stage to be optional

Sources/ProjectSpec/Scheme.swift

@@ -8,7 +8,7 @@ public typealias BuildType = XCScheme.BuildAction.Entry.BuildFor
 public struct Scheme: Equatable {
 
     public var name: String
-    public var build: Build
+    public var build: Build!
     public var run: Run?
     public var archive: Archive?
     public var analyze: Analyze?
@@ -17,7 +17,7 @@ public struct Scheme: Equatable {
 
     public init(
         name: String,
-        build: Build,
+        build: Build? = nil,
         run: Run? = nil,
         test: Test? = nil,
         profile: Profile? = nil,
@@ -712,7 +712,7 @@ extension Scheme: NamedJSONDictionaryConvertible {
 
     public init(name: String, jsonDictionary: JSONDictionary) throws {
         self.name = name
-        build = try jsonDictionary.json(atKeyPath: "build")
+        build = jsonDictionary.json(atKeyPath: "build")
         run = jsonDictionary.json(atKeyPath: "run")
         test = jsonDictionary.json(atKeyPath: "test")
         analyze = jsonDictionary.json(atKeyPath: "analyze")
@@ -724,7 +724,7 @@ extension Scheme: NamedJSONDictionaryConvertible {
 extension Scheme: JSONEncodable {
     public func toJSONValue() -> Any {
         [
-            "build": build.toJSONValue(),
+            "build": build?.toJSONValue(),
             "run": run?.toJSONValue(),
             "test": test?.toJSONValue(),
             "analyze": analyze?.toJSONValue(),

Sources/ProjectSpec/SpecValidation.swift

@@ -182,9 +182,11 @@ extension Project {
         }
 
         for scheme in schemes {
-            errors.append(
-                contentsOf: scheme.build.targets.compactMap { validationError(for: $0.target, in: scheme, action: "build") }
-            )
+            if let action = scheme.build {
+                errors.append(contentsOf: action.targets.compactMap {
+                    validationError(for: $0.target, in: scheme, action: "build")
+                })
+            }
             if let action = scheme.run, let config = action.config, getConfig(config) == nil {
                 errors.append(.invalidSchemeConfig(scheme: scheme.name, config: config))
             }

Sources/XcodeGenKit/SchemeGenerator.swift

@@ -167,7 +167,7 @@ public class SchemeGenerator {
 
         let testBuildTargetEntries = try testBuildTargets.map(getBuildEntry)
 
-        let buildActionEntries: [XCScheme.BuildAction.Entry] = try scheme.build.targets.map(getBuildEntry)
+        let buildActionEntries: [XCScheme.BuildAction.Entry] = try scheme.build?.targets.map(getBuildEntry) ?? []
 
         func getExecutionAction(_ action: Scheme.ExecutionAction) -> XCScheme.ExecutionAction {
             // ExecutionActions can require the use of build settings. Xcode allows the settings to come from a build or test target.
@@ -183,27 +183,42 @@ public class SchemeGenerator {
 
         if let targetName = scheme.run?.executable {
             schemeTarget = project.getTarget(targetName)
-        } else {
-            guard let firstTarget = scheme.build.targets.first else {
-                throw SchemeGenerationError.missingBuildTargets(scheme.name)
-            }
-            let name = scheme.build.targets.first { $0.buildTypes.contains(.running) }?.target.name ?? firstTarget.target.name
+        } else if
+            let targets = scheme.build?.targets,
+            let firstTarget = targets.first
+        {
+            let name = targets.first { $0.buildTypes.contains(.running) }?.target.name ?? firstTarget.target.name
             schemeTarget = target ?? project.getTarget(name)
+        } else {
+            schemeTarget = nil
         }
 
         let shouldExecuteOnLaunch = schemeTarget?.shouldExecuteOnLaunch == true
+        let buildableReference: XCScheme.BuildableReference?
+        let buildAction: XCScheme.BuildAction?
+        let runnables: (launch: XCScheme.Runnable, profile: XCScheme.BuildableProductRunnable)?
+
+        if let buildableReferenceCandidate = buildActionEntries.first(where: { $0.buildableReference.blueprintName == schemeTarget?.name })?.buildableReference ?? buildActionEntries.first?.buildableReference
+        {
+            runnables = makeProductRunnables(for: schemeTarget, buildableReference: buildableReferenceCandidate)
+
+            buildableReference = buildableReferenceCandidate
+            buildAction = scheme.build.flatMap { build in
+                XCScheme.BuildAction(
+                    buildActionEntries: buildActionEntries,
+                    preActions: build.preActions.map(getExecutionAction),
+                    postActions: build.postActions.map(getExecutionAction),
+                    parallelizeBuild: build.parallelizeBuild,
+                    buildImplicitDependencies: build.buildImplicitDependencies,
+                    runPostActionsOnFailure: build.runPostActionsOnFailure
+                )
+            }
+        } else {
+            buildableReference = nil
+            buildAction = nil
+            runnables = nil
+        }
 
-        let buildableReference = buildActionEntries.first(where: { $0.buildableReference.blueprintName == schemeTarget?.name })?.buildableReference ?? buildActionEntries.first!.buildableReference
-        let runnables = makeProductRunnables(for: schemeTarget, buildableReference: buildableReference)
-
-        let buildAction = XCScheme.BuildAction(
-            buildActionEntries: buildActionEntries,
-            preActions: scheme.build.preActions.map(getExecutionAction),
-            postActions: scheme.build.postActions.map(getExecutionAction),
-            parallelizeBuild: scheme.build.parallelizeBuild,
-            buildImplicitDependencies: scheme.build.buildImplicitDependencies,
-            runPostActionsOnFailure: scheme.build.runPostActionsOnFailure
-        )
 
         let testables: [XCScheme.TestableReference] = zip(testTargets, testBuildTargetEntries).map { testTarget, testBuildEntries in
 
@@ -298,7 +313,7 @@ public class SchemeGenerator {
         }
 
         let launchAction = XCScheme.LaunchAction(
-            runnable: shouldExecuteOnLaunch ? runnables.launch : nil,
+            runnable: shouldExecuteOnLaunch ? runnables?.launch : nil,
             buildConfiguration: scheme.run?.config ?? defaultDebugConfig.name,
             preActions: scheme.run?.preActions.map(getExecutionAction) ?? [],
             postActions: scheme.run?.postActions.map(getExecutionAction) ?? [],
@@ -321,7 +336,7 @@ public class SchemeGenerator {
         )
 
         let profileAction = XCScheme.ProfileAction(
-            buildableProductRunnable: shouldExecuteOnLaunch ? runnables.profile : nil,
+            buildableProductRunnable: shouldExecuteOnLaunch ? runnables?.profile : nil,
             buildConfiguration: scheme.profile?.config ?? defaultReleaseConfig.name,
             preActions: scheme.profile?.preActions.map(getExecutionAction) ?? [],
             postActions: scheme.profile?.postActions.map(getExecutionAction) ?? [],
@@ -403,16 +418,13 @@ enum SchemeGenerationError: Error, CustomStringConvertible {
     case missingTarget(TargetReference, projectPath: String)
     case missingPackage(String)
     case missingProject(String)
-    case missingBuildTargets(String)
 
     var description: String {
         switch self {
         case .missingTarget(let target, let projectPath):
             return "Unable to find target named \"\(target)\" in \"\(projectPath)\""
         case .missingProject(let project):
             return "Unable to find project reference named \"\(project)\" in project.yml"
-        case .missingBuildTargets(let name):
-            return "Unable to find at least one build target in scheme \"\(name)\""
         case .missingPackage(let package):
             return "Unable to find swift package named \"\(package)\" in project.yml"
         }

Tests/Fixtures/test_only.yml

@@ -0,0 +1,12 @@
+name: TestOnly
+targets:
+  Target:
+    type: application
+    platform: iOS
+    sources:
+      - Target
+schemes:
+  TestOnly:
+    test:
+      targets:
+      - Target

Tests/ProjectSpecTests/SpecLoadingTests.swift

@@ -75,6 +75,15 @@ class SpecLoadingTests: XCTestCase {
                 ]
             }
 
+            $0.it("accepts schemes that have no build phase") {
+                let path = fixturePath + "test_only.yml"
+                let project = try loadSpec(path: path)
+                try expect(project.name) == "TestOnly"
+                try expect(project.schemes.count) == 1
+                try expect(project.schemes.first?.build).to.beNil()
+                try expect(project.schemes.first?.test?.targets.first?.name) == "Target"
+            }
+
             $0.it("expands directories") {
                 let path = fixturePath + "paths_test.yml"
                 let project = try loadSpec(path: path)