Chore: Move remaining web framework code to pkg/web, remove macaron binding module (#43018)

* remove macaron binding dependency

* completely purge macaron binding

* move everything to pkg/web

* remove non-go files from pkg/web

* clean up leftovers of macaron imports

* make linter happy

pkg/web/binding_test.go

@@ -0,0 +1,101 @@
+package web
+
+import (
+	"errors"
+	"testing"
+)
+
+type StructWithInt struct {
+	A int `binding:"Required"`
+}
+
+type StructWithPrimitives struct {
+	A int     `binding:"Required"`
+	B string  `binding:"Required"`
+	C bool    `binding:"Required"`
+	D float64 `binding:"Required"`
+}
+
+type StructWithPrivateFields struct {
+	A int `binding:"Required"` // must be validated
+	b int `binding:"Required"` // will not be used
+}
+
+type StructWithInterface struct {
+	A interface{} `binding:"Required"`
+}
+type StructWithSliceInts struct {
+	A []int `binding:"Required"`
+}
+type StructWithSliceStructs struct {
+	A []StructWithInt `binding:"Required"`
+}
+type StructWithSliceInterfaces struct {
+	A []interface{} `binding:"Required"`
+}
+type StructWithStruct struct {
+	A StructWithInt `binding:"Required"`
+}
+type StructWithStructPointer struct {
+	A *StructWithInt `binding:"Required"`
+}
+type StructWithValidation struct {
+	A int
+}
+
+func (sv StructWithValidation) Validate() error {
+	if sv.A < 10 {
+		return errors.New("too small")
+	}
+	return nil
+}
+
+func TestValidationSuccess(t *testing.T) {
+	for _, x := range []interface{}{
+		42,
+		"foo",
+		struct{ A int }{},
+		StructWithInt{42},
+		StructWithPrimitives{42, "foo", true, 12.34},
+		StructWithPrivateFields{12, 0},
+		StructWithInterface{"foo"},
+		StructWithSliceInts{[]int{1, 2, 3}},
+		StructWithSliceInterfaces{[]interface{}{1, 2, 3}},
+		StructWithSliceStructs{[]StructWithInt{{1}, {2}}},
+		StructWithStruct{StructWithInt{3}},
+		StructWithStructPointer{&StructWithInt{3}},
+		StructWithValidation{42},
+	} {
+		if err := validate(x); err != nil {
+			t.Error("Validation failed:", x, err)
+		}
+	}
+}
+func TestValidationFailure(t *testing.T) {
+	for i, x := range []interface{}{
+		StructWithInt{0},
+		StructWithPrimitives{0, "foo", true, 12.34},
+		StructWithPrimitives{42, "", true, 12.34},
+		StructWithPrimitives{42, "foo", false, 12.34},
+		StructWithPrimitives{42, "foo", true, 0},
+		StructWithPrivateFields{0, 1},
+		StructWithInterface{},
+		StructWithInterface{nil},
+		StructWithSliceInts{},
+		StructWithSliceInts{[]int{}},
+		StructWithSliceStructs{[]StructWithInt{}},
+		StructWithSliceStructs{[]StructWithInt{{0}, {2}}},
+		StructWithSliceStructs{[]StructWithInt{{2}, {0}}},
+		StructWithSliceInterfaces{[]interface{}{}},
+		StructWithSliceInterfaces{nil},
+		StructWithStruct{StructWithInt{}},
+		StructWithStruct{StructWithInt{0}},
+		StructWithStructPointer{},
+		StructWithStructPointer{&StructWithInt{}},
+		StructWithValidation{2},
+	} {
+		if err := validate(x); err == nil {
+			t.Error("Validation should fail:", i, x)
+		}
+	}
+}