Do pass explicit empty argument to -XCTest (#3631)

neonichu · web-flow · commit fbcf039d10d1 · 2021-07-21T15:42:58.000-07:00
Right now if no tests are matching after filter/skip/etc, we pass no argument to `XCTest` which actually crashes the `xctest` CLI. This makes it so we instead pass an explicit empty argument to it.
diff --git a/Sources/Commands/SwiftTestTool.swift b/Sources/Commands/SwiftTestTool.swift
@@ -284,9 +284,10 @@ public struct SwiftTestTool: SwiftCommand {
                 // If there were no matches, emit a warning.
                 if tests.isEmpty {
                     swiftTool.diagnostics.emit(.noMatchingTests)
+                    xctestArg = "''"
+                } else {
+                    xctestArg = tests.map { $0.specifier }.joined(separator: ",")
                 }
-
-                xctestArg = tests.map { $0.specifier }.joined(separator: ",")
             }
 
             let runner = TestRunner(

Original file line number	Diff line number	Diff line change
`@@ -284,9 +284,10 @@ public struct SwiftTestTool: SwiftCommand {`
`284`	`284`	`// If there were no matches, emit a warning.`
`285`	`285`	`if tests.isEmpty {`
`286`	`286`	`swiftTool.diagnostics.emit(.noMatchingTests)`
	`287`	`+ xctestArg = "''"`
	`288`	`+ } else {`
	`289`	`+ xctestArg = tests.map { $0.specifier }.joined(separator: ",")`
`287`	`290`	`}`
`288`		`-`
`289`		`- xctestArg = tests.map { $0.specifier }.joined(separator: ",")`
`290`	`291`	`}`
`291`	`292`
`292`	`293`	`let runner = TestRunner(`