ADD - test to verify clang is relative to the swift compiler path.

UPDATE - XCTestManifests.swift

Author: JhonnyBillM

Sources/SwiftDriver/Toolchains/Toolchain.swift

@@ -114,7 +114,8 @@ extension Toolchain {
     } else if let path = lookupExecutablePath(filename: exec, searchPaths: searchPaths) {
       return path
     } else {
-      throw ToolchainError.unableToFind(tool: exec)
+      // This is a hack so our tests work on linux. We need a better way for looking up tools in general.
+      return AbsolutePath("/usr/bin/" + exec)
     }
   }
 
@@ -126,8 +127,7 @@ extension Toolchain {
     ).spm_chomp()
     return AbsolutePath(path)
   #else
-    // This is a hack so our tests work on linux. We need a better way for looking up tools in general.
-    return AbsolutePath("/usr/bin/" + exec)
+    throw ToolchainError.unableToFind(tool: exec)
   #endif
   }
 }

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -893,6 +893,21 @@ final class SwiftDriverTests: XCTestCase {
     assertString(swiftVersion, contains: "Swift version ")
   #endif
   }
+  
+  func testToolchainClangPath() {
+    // TODO: remove this conditional check once DarwinToolchain does not requires xcrun to look for clang.
+    var toolchain: Toolchain
+    #if os(macOS)
+    toolchain = DarwinToolchain(env: ProcessEnv.vars)
+    #else
+    toolchain = GenericUnixToolchain(env: ProcessEnv.vars)
+    #endif
+    
+    XCTAssertEqual(
+      try? toolchain.getToolPath(.swiftCompiler).parentDirectory,
+      try? toolchain.getToolPath(.clang).parentDirectory
+    )
+  }
 }
 
 func assertString(

Tests/SwiftDriverTests/XCTestManifests.swift

@@ -54,6 +54,17 @@ extension PrefixTrieTests {
     ]
 }
 
+extension StringAdditionsTests {
+    // DO NOT MODIFY: This is autogenerated, use:
+    //   `swift test --generate-linuxmain`
+    // to regenerate.
+    static let __allTests__StringAdditionsTests = [
+        ("testBasicIdentifiers", testBasicIdentifiers),
+        ("testSwiftKeywordsAsIdentifiers", testSwiftKeywordsAsIdentifiers),
+        ("testUnicodeCharacters", testUnicodeCharacters),
+    ]
+}
+
 extension SwiftDriverTests {
     // DO NOT MODIFY: This is autogenerated, use:
     //   `swift test --generate-linuxmain`
@@ -70,16 +81,21 @@ extension SwiftDriverTests {
         ("testMergeModulesOnly", testMergeModulesOnly),
         ("testModuleNameFallbacks", testModuleNameFallbacks),
         ("testModuleSettings", testModuleSettings),
+        ("testMultithreading", testMultithreading),
+        ("testMultithreadingDiagnostics", testMultithreadingDiagnostics),
         ("testOutputFileMapLoading", testOutputFileMapLoading),
         ("testOutputFileMapStoring", testOutputFileMapStoring),
         ("testParseErrors", testParseErrors),
         ("testParsing", testParsing),
         ("testPrimaryOutputKinds", testPrimaryOutputKinds),
+        ("testPrimaryOutputKindsDiagnostics", testPrimaryOutputKindsDiagnostics),
         ("testRegressions", testRegressions),
         ("testResponseFileExpansion", testResponseFileExpansion),
+        ("testResponseFileTokenization", testResponseFileTokenization),
         ("testSanitizerArgs", testSanitizerArgs),
         ("testStandardCompileJobs", testStandardCompileJobs),
         ("testTargetTriple", testTargetTriple),
+        ("testToolchainClangPath", testToolchainClangPath),
         ("testToolchainUtilities", testToolchainUtilities),
     ]
 }
@@ -109,6 +125,7 @@ public func __allTests() -> [XCTestCaseEntry] {
         testCase(JobExecutorTests.__allTests__JobExecutorTests),
         testCase(ParsableMessageTests.__allTests__ParsableMessageTests),
         testCase(PrefixTrieTests.__allTests__PrefixTrieTests),
+        testCase(StringAdditionsTests.__allTests__StringAdditionsTests),
         testCase(SwiftDriverTests.__allTests__SwiftDriverTests),
         testCase(TripleTests.__allTests__TripleTests),
     ]