Pass all arguments when initing testing parameters in swift build (#7396)

Ensures that a fully-initialized `TestingParameters` structure is used
with `swift build --build-tests` instead of using any default parameters
(which will tend us toward the wrong output with packages that use
`--enable-test-discovery` and still have LinuxMain.swift files.)

Tested with swift-numerics on Ubuntu 22.04 aarch64; before the change,
we'd hit the `fatalError()` call in that package's LinuxMain.swift file.
After the change, we correctly run XCTest-based tests.

Resolves #7389.

Author: grynspan

Fixtures/Miscellaneous/TestDiscovery/IgnoresLinuxMain/Package.swift

@@ -0,0 +1,9 @@
+// swift-tools-version:5.10
+import PackageDescription
+
+let package = Package(
+    name: "IgnoresLinuxMain",
+    targets: [
+        .testTarget(name: "IgnoresLinuxMainTests"),
+    ]
+)

Fixtures/Miscellaneous/TestDiscovery/IgnoresLinuxMain/Tests/IgnoresLinuxMainTests/SomeTest.swift

@@ -0,0 +1,5 @@
+import XCTest
+
+final class SomeTests: XCTestCase {
+    func testSomething() {}
+}

Fixtures/Miscellaneous/TestDiscovery/IgnoresLinuxMain/Tests/LinuxMain.swift

@@ -0,0 +1 @@
+fatalError("Should not use the contents of LinuxMain.swift")

Sources/Commands/SwiftBuildCommand.swift

@@ -154,6 +154,11 @@ package struct SwiftBuildCommand: AsyncSwiftCommand {
                 buildParameters.testingParameters = .init(
                     configuration: buildParameters.configuration,
                     targetTriple: buildParameters.triple,
+                    enableCodeCoverage: buildParameters.testingParameters.enableCodeCoverage,
+                    enableTestability: buildParameters.testingParameters.enableTestability,
+                    experimentalTestOutput: buildParameters.testingParameters.experimentalTestOutput,
+                    forceTestDiscovery: globalOptions.build.enableTestDiscovery,
+                    testEntryPointPath: globalOptions.build.testEntryPointPath,
                     library: library
                 )
                 try build(swiftCommandState, subset: subset, buildParameters: buildParameters)

Tests/CommandsTests/BuildCommandTests.swift

@@ -42,10 +42,14 @@ final class BuildCommandTests: CommandsTestCase {
         try SwiftPM.Build.execute(args, packagePath: packagePath, env: environment)
     }
 
-    func build(_ args: [String], packagePath: AbsolutePath? = nil, isRelease: Bool = false) throws -> BuildResult {
+    func build(_ args: [String], packagePath: AbsolutePath? = nil, isRelease: Bool = false, cleanAfterward: Bool = true) throws -> BuildResult {
         let buildConfigurationArguments = isRelease ? ["-c", "release"] : []
         let (stdout, stderr) = try execute(args + buildConfigurationArguments, packagePath: packagePath)
-        defer { try! SwiftPM.Package.execute(["clean"], packagePath: packagePath) }
+        defer {
+            if cleanAfterward {
+                try! SwiftPM.Package.execute(["clean"], packagePath: packagePath)
+            }
+        }
         let (binPathOutput, _) = try execute(
             ["--show-bin-path"] + buildConfigurationArguments,
             packagePath: packagePath
@@ -644,4 +648,20 @@ final class BuildCommandTests: CommandsTestCase {
             XCTAssertNoMatch(buildResult.stdout, .contains("codesign --force --sign - --entitlements"))
         }
     }
+
+#if !canImport(Darwin)
+    func testIgnoresLinuxMain() throws {
+        try fixture(name: "Miscellaneous/TestDiscovery/IgnoresLinuxMain") { fixturePath in
+            let buildResult = try self.build(["-v", "--build-tests", "--enable-test-discovery"], packagePath: fixturePath, cleanAfterward: false)
+            let testBinaryPath = buildResult.binPath.appending("IgnoresLinuxMainPackageTests.xctest")
+
+            let processTerminated = expectation(description: "Process terminated")
+            _ = try Process.run(testBinaryPath.asURL, arguments: [] ) { process in
+               XCTAssertEqual(process.terminationStatus, EXIT_SUCCESS)
+               processTerminated.fulfill()
+            }
+            wait(for: [processTerminated], timeout: .infinity)
+        }
+    }
+#endif
 }