feat(checker): port other checkers over

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/checker/headerexists/checker_test.go

@@ -0,0 +1,57 @@
+package headerexists
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"testing"
+)
+
+func TestChecker(t *testing.T) {
+	fac := Factory{}
+
+	for _, tt := range []struct {
+		name      string
+		header    string
+		reqHeader string
+		ok        bool
+	}{
+		{
+			name:      "match",
+			header:    "Authorization",
+			reqHeader: "Authorization",
+			ok:        true,
+		},
+		{
+			name:      "not_match",
+			header:    "Authorization",
+			reqHeader: "Authentication",
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			hec, err := fac.Build(t.Context(), json.RawMessage(fmt.Sprintf("%q", tt.header)))
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			t.Log(hec.Hash())
+
+			r, err := http.NewRequest(http.MethodGet, "/", nil)
+			if err != nil {
+				t.Fatalf("can't make request: %v", err)
+			}
+
+			r.Header.Set(tt.reqHeader, "hunter2")
+
+			ok, err := hec.Check(r)
+
+			if tt.ok != ok {
+				t.Errorf("ok: %v, wanted: %v", ok, tt.ok)
+			}
+
+			if err != nil {
+				t.Errorf("err: %v", err)
+			}
+		})
+	}
+}