Allow skipping tests with a flag, instead of the environment variable

Author: finagolfin

Sources/Commands/SwiftTestTool.swift

@@ -420,6 +420,11 @@ public class SwiftTestTool: SwiftTool<TestToolOptions> {
                     "<test-target>.<test-case>/<test>"),
             to: { $0._testCaseSpecifier = .regex($1) })
 
+        binder.bind(
+            option: parser.add(option: "--skip", kind: String.self,
+                usage: "Skip test cases that match a colon-separated list of regular expressions, Example: --skip Performance:Scrypt"),
+            to: { $0._testCaseSpecifier = .skip($1.split(separator: ":", omittingEmptySubsequences: true).map(String.init)) })
+
         binder.bind(
             option: parser.add(option: "--enable-code-coverage", kind: Bool.self,
                 usage: "Test with code coverage enabled"),
@@ -1086,6 +1091,6 @@ final class XUnitGenerator {
 
 private extension Diagnostic.Message {
     static var noMatchingTests: Diagnostic.Message {
-        .warning("'--filter' predicate did not match any test case")
+        .warning("No matching test cases were run")
     }
 }