Add internal/kctl and internal/config packages with unit tests

internal/config/config_test.go

@@ -0,0 +1,44 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoad_MissingFileReturnsDefaults(t *testing.T) {
+	cfg, err := Load(filepath.Join(t.TempDir(), "does-not-exist.yaml"))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(cfg.ContextPairs) != 0 {
+		t.Fatalf("expected no context pairs, got %v", cfg.ContextPairs)
+	}
+	if cfg.TeamLabelKey != "" {
+		t.Fatalf("expected empty team label key, got %q", cfg.TeamLabelKey)
+	}
+}
+
+func TestLoad_ValidFile(t *testing.T) {
+	content := []byte(`
+context_pairs:
+  - name: "env-pair-1"
+    contexts: ["ctx-a", "ctx-b"]
+team_label_key: "example.org/team"
+`)
+	path := filepath.Join(t.TempDir(), "config.yaml")
+	if err := os.WriteFile(path, content, 0o600); err != nil {
+		t.Fatalf("failed to write test config: %v", err)
+	}
+
+	cfg, err := Load(path)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if cfg.TeamLabelKey != "example.org/team" {
+		t.Fatalf("unexpected team label key: %q", cfg.TeamLabelKey)
+	}
+	if len(cfg.ContextPairs) != 1 || cfg.ContextPairs[0].Name != "env-pair-1" {
+		t.Fatalf("unexpected context pairs: %v", cfg.ContextPairs)
+	}
+}