add flag to allow disabling building with testablity when building tests

motivation: allow building tests without testability (testable imports), this can increase build / test cycles when tests do not require the testable imports feature since more is cachable

changes:
* add a --disable-testable-imports flag to "swift test" with which tests are build without the testablity feature
* add tests

rdar://82448144

Sources/Commands/SwiftTestTool.swift

@@ -138,6 +138,10 @@ struct TestToolOptions: ParsableArguments {
     @Option(help: "Test the specified product.")
     var testProduct: String?
 
+    /// Generate LinuxMain entries and exit.
+    @Flag(name: .customLong("testable-imports"), inversion: .prefixedEnableDisable, help: "Enable or disable testable imports. Enabled by default.")
+    var enableTestableImports: Bool = true
+
     /// Returns the test case specifier if overridden in the env.
     private func testCaseSkipOverride() -> TestCaseSpecifier? {
         guard let override = ProcessEnv.vars["_SWIFTPM_SKIP_TESTS_LIST"] else {
@@ -235,7 +239,7 @@ public struct SwiftTestTool: SwiftCommand {
             guard let rootManifest = rootManifests.values.first else {
                 throw StringError("invalid manifests at \(root.packages)")
             }
-            let buildParameters = try swiftTool.buildParametersForTest()
+            let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
             print(codeCovAsJSONPath(buildParameters: buildParameters, packageName: rootManifest.displayName))
 
         case .generateLinuxMain:
@@ -256,7 +260,7 @@ public struct SwiftTestTool: SwiftCommand {
         case .runSerial:
             let toolchain = try swiftTool.getToolchain()
             let testProducts = try buildTestsIfNeeded(swiftTool: swiftTool)
-            let buildParameters = try swiftTool.buildParametersForTest()
+            let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
 
             // Clean out the code coverage directory that may contain stale
             // profraw files from a previous run of the code coverage tool.
@@ -324,7 +328,7 @@ public struct SwiftTestTool: SwiftCommand {
             let tests = try testSuites
                 .filteredTests(specifier: options.testCaseSpecifier)
                 .skippedTests(specifier: options.testCaseSkip)
-            let buildParameters = try swiftTool.buildParametersForTest()
+            let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
 
             // If there were no matches, emit a warning and exit.
             if tests.isEmpty {
@@ -380,7 +384,7 @@ public struct SwiftTestTool: SwiftCommand {
         // Merge all the profraw files to produce a single profdata file.
         try mergeCodeCovRawDataFiles(swiftTool: swiftTool)
 
-        let buildParameters = try swiftTool.buildParametersForTest()
+        let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
         for product in testProducts {
             // Export the codecov data as JSON.
             let jsonPath = codeCovAsJSONPath(
@@ -396,7 +400,7 @@ public struct SwiftTestTool: SwiftCommand {
         let llvmProf = try swiftTool.getToolchain().getLLVMProf()
 
         // Get the profraw files.
-        let buildParameters = try swiftTool.buildParametersForTest()
+        let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
         let codeCovFiles = try localFileSystem.getDirectoryContents(buildParameters.codeCovPath)
 
         // Construct arguments for invoking the llvm-prof tool.
@@ -420,7 +424,7 @@ public struct SwiftTestTool: SwiftCommand {
     private func exportCodeCovAsJSON(to path: AbsolutePath, testBinary: AbsolutePath, swiftTool: SwiftTool) throws {
         // Export using the llvm-cov tool.
         let llvmCov = try swiftTool.getToolchain().getLLVMCov()
-        let buildParameters = try swiftTool.buildParametersForTest()
+        let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
         let args = [
             llvmCov.pathString,
             "export",
@@ -440,7 +444,8 @@ public struct SwiftTestTool: SwiftCommand {
     ///
     /// - Returns: The paths to the build test products.
     private func buildTestsIfNeeded(swiftTool: SwiftTool) throws -> [BuiltTestProduct] {
-        let buildSystem = try swiftTool.createBuildSystem(buildParameters: swiftTool.buildParametersForTest())
+        let buildParameters = try swiftTool.buildParametersForTest(options: self.options)
+        let buildSystem = try swiftTool.createBuildSystem(buildParameters: buildParameters)
 
         if options.shouldBuildTests {
             let subset = options.testProduct.map(BuildSubset.product) ?? .allIncludingTests
@@ -1016,8 +1021,17 @@ final class XUnitGenerator {
     }
 }
 
+extension SwiftTool {
+    func buildParametersForTest(options: TestToolOptions) throws -> BuildParameters {
+        try self.buildParametersForTest(
+            enableTestability: options.enableTestableImports
+        )
+    }
+}
+
 private extension Basics.Diagnostic {
     static var noMatchingTests: Self {
         .warning("No matching test cases were run")
     }
 }
+

Sources/Commands/TestingSupport.swift

@@ -134,10 +134,12 @@ enum TestingSupport {
 }
 
 extension SwiftTool {
-    func buildParametersForTest() throws -> BuildParameters {
+    func buildParametersForTest(
+        enableTestability: Bool? = nil
+    ) throws -> BuildParameters {
         var parameters = try self.buildParameters()
-        // for test commands, alway enable building with testability enabled
-        parameters.enableTestability = true
+        // for test commands, we normally enable building with testability
+        parameters.enableTestability = enableTestability ?? true
         return parameters
     }
 }

Tests/CommandsTests/TestToolTests.swift

@@ -8,15 +8,15 @@
  See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 */
 
-import XCTest
-
-import SPMTestSupport
 import Commands
+import SPMTestSupport
+import TSCBasic
+import XCTest
 
 final class TestToolTests: CommandsTestCase {
 
-    private func execute(_ args: [String]) throws -> (stdout: String, stderr: String) {
-        return try SwiftPMProduct.SwiftTest.execute(args)
+    private func execute(_ args: [String], packagePath: AbsolutePath? = nil) throws -> (stdout: String, stderr: String) {
+        return try SwiftPMProduct.SwiftTest.execute(args, packagePath: packagePath)
     }
 
     func testUsage() throws {
@@ -58,4 +58,26 @@ final class TestToolTests: CommandsTestCase {
         }
         #endif
     }
+
+    func testEnableDisableTestability() {
+        fixture(name: "Miscellaneous/TestableExe") { path in
+            do {
+                let result = try execute(["--vv"], packagePath: path)
+                // default should run with testability
+                XCTAssertMatch(result.stdout, .contains("-enable-testing"))
+            }
+
+            do {
+                // disable
+                let result = try execute(["--disable-testable-imports", "--vv"], packagePath: path)
+                XCTAssertNoMatch(result.stdout, .contains("-enable-testing"))
+            }
+
+            do {
+                // enable
+                let result = try execute(["--enable-testable-imports", "--vv"], packagePath: path)
+                XCTAssertMatch(result.stdout, .contains("-enable-testing"))
+            }
+        }
+    }
 }