Reword the skip message for the abstract test classes

Author: cmcgee1024

Tests/BuildTests/BuildPlanTests.swift

@@ -47,7 +47,7 @@ extension Build.BuildPlan {
 
 class BuildPlanTestCase: BuildSystemProviderTestCase {
     override func setUpWithError() throws {
-        try XCTSkipIf(type(of: self) == BuildPlanTestCase.self, "Pay no attention to the class behind the curtain.")
+        try XCTSkipIf(type(of: self) == BuildPlanTestCase.self, "Skipping this test since it will be run in subclasses that will provide different build systems to test.")
     }
 
     let inputsDir = AbsolutePath(#file).parentDirectory.appending(components: "Inputs")

Tests/CommandsTests/APIDiffTests.swift

@@ -27,7 +27,7 @@ import XCTest
 
 class APIDiffTestCase: CommandsBuildProviderTestCase {
     override func setUpWithError() throws {
-        try XCTSkipIf(type(of: self) == APIDiffTestCase.self, "Pay no attention to the class behind the curtain.")
+        try XCTSkipIf(type(of: self) == APIDiffTestCase.self, "Skipping this test since it will be run in subclasses that will provide different build systems to test.")
     }
 
     @discardableResult
@@ -481,4 +481,4 @@ class APIDiffSwiftBuildTests: APIDiffTestCase {
     override func skipIfApiDigesterUnsupportedOrUnset() throws {
         try super.skipIfApiDigesterUnsupportedOrUnset()
     }
-}
+}

Tests/CommandsTests/BuildCommandTests.swift

@@ -34,7 +34,7 @@ struct BuildResult {
 class BuildCommandTestCases: CommandsBuildProviderTestCase {
 
     override func setUpWithError() throws {
-        try XCTSkipIf(type(of: self) == BuildCommandTestCases.self, "Pay no attention to the class behind the curtain.")
+        try XCTSkipIf(type(of: self) == BuildCommandTestCases.self, "Skipping this test since it will be run in subclasses that will provide different build systems to test.")
     }
 
     @discardableResult

Tests/CommandsTests/PackageCommandTests.swift

@@ -33,7 +33,7 @@ import class Basics.AsyncProcess
 
 class PackageCommandTestCase: CommandsBuildProviderTestCase {
     override func setUpWithError() throws {
-        try XCTSkipIf(type(of: self) == PackageCommandTestCase.self, "Pay no attention to the class behind the curtain.")
+        try XCTSkipIf(type(of: self) == PackageCommandTestCase.self, "Skipping this test since it will be run in subclasses that will provide different build systems to test.")
     }
 
     @discardableResult

Tests/CommandsTests/RunCommandTests.swift

@@ -21,7 +21,7 @@ import class Basics.AsyncProcess
 
 class RunCommandTestCase: CommandsBuildProviderTestCase {
     override func setUpWithError() throws {
-        try XCTSkipIf(type(of: self) == RunCommandTestCase.self, "Pay no attention to the class behind the curtain.")
+        try XCTSkipIf(type(of: self) == RunCommandTestCase.self, "Skipping this test since it will be run in subclasses that will provide different build systems to test.")
     }
 
     private func execute(

Tests/CommandsTests/TestCommandTests.swift

@@ -20,7 +20,7 @@ import XCTest
 
 class TestCommandTestCase: CommandsBuildProviderTestCase {
     override func setUpWithError() throws {
-        try XCTSkipIf(type(of: self) == TestCommandTestCase.self, "Pay no attention to the class behind the curtain.")
+        try XCTSkipIf(type(of: self) == TestCommandTestCase.self, "Skipping this test since it will be run in subclasses that will provide different build systems to test.")
     }
 
     private func execute(