test: add mapping tests for dns_search and build target and fix implementation

Author: explicitcontextualunderstanding

Sources/Container-Compose/Commands/ComposeUp.swift

@@ -640,6 +640,12 @@ extension ComposeUp {
             runArgs.append(runtime)
         }
 
+        // Map dns search if present
+        if let dnsSearch = service.dns_search {
+            runArgs.append("--dns-search")
+            runArgs.append(dnsSearch)
+        }
+
         // Map init flag if present (support both explicit Bool and optional presence)
         // Note: Specifying init_image also implies --init
         if service.`init` == true || service.init_image != nil {

Tests/Container-Compose-StaticTests/BuildConfigurationTests.swift

@@ -65,6 +65,20 @@ struct BuildConfigurationTests {
         #expect(build.args?["NODE_VERSION"] == "18")
         #expect(build.args?["ENV"] == "production")
     }
+
+    @Test("Parse build with target stage")
+    func parseBuildWithTarget() throws {
+        let yaml = """
+        context: .
+        target: builder
+        """
+
+        let decoder = YAMLDecoder()
+        let build = try decoder.decode(Build.self, from: yaml)
+
+        #expect(build.context == ".")
+        #expect(build.target == "builder")
+    }
 
 
     @Test("Service with build configuration")

Tests/Container-Compose-StaticTests/ComposeUpMappingTests.swift

@@ -120,4 +120,20 @@ final class ComposeUpMappingTests: XCTestCase {
 
         XCTAssertTrue(entryIdx < imageIdx, "Expected --entrypoint to appear before image, but args: \(args)")
     }
+
+    func testDNSSearchMapping() throws {
+        let yaml = """
+        services:
+          app:
+            image: busybox:latest
+            dns_search: "my-namespace.local"
+        """
+        let dockerCompose = try YAMLDecoder().decode(DockerCompose.self, from: yaml)
+        guard let service = dockerCompose.services["app"] ?? nil else { return XCTFail("Service 'app' missing") }
+
+        let args = try ComposeUp.makeRunArgs(service: service, serviceName: "app", image: nil, dockerCompose: dockerCompose, projectName: "proj", detach: false, cwd: "/tmp", environmentVariables: [:])
+
+        XCTAssertTrue(args.contains("--dns-search"), "Expected --dns-search flag present in args: \(args)")
+        XCTAssertTrue(args.contains("my-namespace.local"), "Expected dns search value present in args: \(args)")
+    }
 }