Link test command test failures on Linux to issue (#8459)

The TestCommandTests fail on Linux due to a common linker problem with
swift build build system, which is the missing 'main' symbol problem. This
is described further detail in #8439.

Provide the link in the skip messages and remove the TODO tags since the
investigation is complete and the reason for the failures is now known.

Update the common test case logic so that it dumps the command execution
stdout and stderr in the case of failure to help diagnose these result.xml failures
immediately in the logs.

Author: cmcgee1024

Tests/CommandsTests/TestCommandTests.swift

@@ -225,8 +225,8 @@ class TestCommandTestCase: CommandsBuildProviderTestCase {
             let xUnitUnderTest = fixturePath.appending("result\(testRunner.fileSuffix).xml")
 
             // WHEN we execute swift-test in parallel while specifying xUnit generation
-            let extraCommandArgs = enableExperimentalFlag ? ["--experimental-xunit-message-failure"]: [],
-            _ = try await execute(
+            let extraCommandArgs = enableExperimentalFlag ? ["--experimental-xunit-message-failure"]: []
+            let (stdout, stderr) = try await execute(
                 [
                     "--parallel",
                     "--verbose",
@@ -239,6 +239,12 @@ class TestCommandTestCase: CommandsBuildProviderTestCase {
                 throwIfCommandFails: false
             )
 
+            if !FileManager.default.fileExists(atPath: xUnitUnderTest.pathString) {
+                // If the build failed then produce a output dump of what happened during the execution
+                print("\(stdout)")
+                print("\(stderr)")
+            }
+
             // THEN we expect \(xUnitUnderTest) to exists
             XCTAssertFileExists(xUnitUnderTest)
             let contents: String = try localFileSystem.readFileContents(xUnitUnderTest)
@@ -694,35 +700,35 @@ class TestCommandSwiftBuildTests: TestCommandTestCase {
 
 #if !os(macOS)
     override func testSwiftTestXMLOutputVerifySingleTestFailureMessageWithFlagDisabledXCTest() async throws {
-        throw XCTSkip("SWBINTTODO: Result XML could not be found. This looks to be a build layout issue. Further investigation is needed.")
+        throw XCTSkip("Result XML could not be found. The build fails due to an LD_LIBRARY_PATH issue finding swift core libraries. https://github.com/swiftlang/swift-package-manager/issues/8416")
     }
 
     override func testSwiftTestXMLOutputVerifyMultipleTestFailureMessageWithFlagEnabledXCTest() async throws {
-        throw XCTSkip("SWBINTTODO: Result XML could not be found. This looks to be a build layout issue. Further investigation is needed.")
+        throw XCTSkip("Result XML could not be found. The build fails due to an LD_LIBRARY_PATH issue finding swift core libraries. https://github.com/swiftlang/swift-package-manager/issues/8416")
     }
 
     override func testSwiftTestXMLOutputVerifySingleTestFailureMessageWithFlagEnabledXCTest() async throws {
-        throw XCTSkip("SWBINTTODO: Result XML could not be found. This looks to be a build layout issue. Further investigation is needed.")
+        throw XCTSkip("Result XML could not be found. The build fails due to an LD_LIBRARY_PATH issue finding swift core libraries. https://github.com/swiftlang/swift-package-manager/issues/8416")
     }
 
     override func testSwiftTestXMLOutputVerifyMultipleTestFailureMessageWithFlagDisabledXCTest() async throws {
-        throw XCTSkip("SWBINTTODO: Result XML could not be found. This looks to be a build layout issue. Further investigation is needed.")
+        throw XCTSkip("Result XML could not be found. The build fails due to an LD_LIBRARY_PATH issue finding swift core libraries. https://github.com/swiftlang/swift-package-manager/issues/8416")
     }
 
     override func testSwiftTestSkip() async throws {
-        throw XCTSkip("SWBINTTODO: This fails due to a linker error on Linux. Further investigation is needed.")
+        throw XCTSkip("This fails due to a linker error on Linux. https://github.com/swiftlang/swift-package-manager/issues/8439")
     }
 
     override func testSwiftTestXMLOutputWhenEmpty() async throws {
-        throw XCTSkip("SWBINTTODO: This fails due to a linker error on Linux 'undefined reference to main'. Further investigation is needed.")
+        throw XCTSkip("This fails due to a linker error on Linux. https://github.com/swiftlang/swift-package-manager/issues/8439")
     }
 
     override func testSwiftTestFilter() async throws {
-        throw XCTSkip("SWBINTTODO: This fails due to an unknown linker error on Linux. Further investigation is needed.")
+        throw XCTSkip("This fails due to an unknown linker error on Linux. https://github.com/swiftlang/swift-package-manager/issues/8439")
     }
 
     override func testSwiftTestParallel() async throws {
-        throw XCTSkip("SWBINTTODO: This fails due to the test expecting specific test output that appears to be empty on Linux. Further investigation is needed.")
+        throw XCTSkip("This fails due to an unknown linker error on Linux. https://github.com/swiftlang/swift-package-manager/issues/8439")
     }
 #endif
 }