completion-tool list-executables should list executable names

Fixtures/Miscellaneous/DifferentProductTargetName/Package.swift

@@ -0,0 +1,12 @@
+// swift-tools-version:5.2
+import PackageDescription
+
+let package = Package(
+    name: "Foo",
+    products: [
+        .executable(name: "Foo", targets: ["Foo"]),
+    ],
+    targets: [
+        .target(name: "Foo", path: "./"),
+    ]
+)

Fixtures/Miscellaneous/DifferentProductTargetName/main.swift

@@ -0,0 +1,3 @@
+public func foo() {
+	{}()
+}

Sources/Commands/PackageCommands/CompletionCommand.swift

@@ -76,7 +76,7 @@ extension SwiftPackageCommand {
             case .listExecutables:
                 let graph = try await swiftCommandState.loadPackageGraph()
                 let package = graph.rootPackages[graph.rootPackages.startIndex].underlying
-                let executables = package.modules.filter { $0.type == .executable }
+                let executables = package.products.filter { $0.type == .executable }
                 for executable in executables {
                     print(executable.name)
                 }

Tests/CommandsTests/CompletionCommandTests.swift

@@ -0,0 +1,27 @@
+import Basics
+import _InternalTestSupport
+import XCTest
+
+final class CompletionCommandTests: CommandsTestCase {
+
+    private func execute(
+        _ args: [String] = [],
+        packagePath: AbsolutePath? = nil
+    ) async throws -> (stdout: String, stderr: String) {
+        return try await SwiftPM.Package.execute(args, packagePath: packagePath)
+    }
+
+    func testListExecutables() async throws {
+        try await fixture(name: "Miscellaneous/MultipleExecutables") { fixturePath in
+            let result = try await execute(["completion-tool", "list-executables"], packagePath: fixturePath)
+            XCTAssertEqual(result.stdout, "exec1\nexec2\n")
+        }
+    }
+
+    func testListExecutablesDifferentNames() async throws {
+        try await fixture(name: "Miscellaneous/DifferentProductTargetName") { fixturePath in
+            let result = try await execute(["completion-tool", "list-executables"], packagePath: fixturePath)
+            XCTAssertEqual(result.stdout, "Foo\n")
+        }
+    }
+}