go context_test 源码
golang context_test 代码
文件路径：/src/go/types/context_test.go
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package types
import (
"go/token"
"testing"
)
func TestContextHashCollisions(t *testing.T) {
if debug {
t.Skip("hash collisions are expected, and would fail debug assertions")
}
// Unit test the de-duplication fall-back logic in Context.
//
// We can't test this via Instantiate because this is only a fall-back in
// case our hash is imperfect.
//
// These lookups and updates use reasonable looking types in an attempt to
// make them robust to internal type assertions, but could equally well use
// arbitrary types.
// Create some distinct origin types. nullaryP and nullaryQ have no
// parameters and are identical (but have different type parameter names).
// unaryP has a parameter.
var nullaryP, nullaryQ, unaryP Type
{
// type nullaryP = func[P any]()
tparam := NewTypeParam(NewTypeName(token.NoPos, nil, "P", nil), &emptyInterface)
nullaryP = NewSignatureType(nil, nil, []*TypeParam{tparam}, nil, nil, false)
}
{
// type nullaryQ = func[Q any]()
tparam := NewTypeParam(NewTypeName(token.NoPos, nil, "Q", nil), &emptyInterface)
nullaryQ = NewSignatureType(nil, nil, []*TypeParam{tparam}, nil, nil, false)
}
{
// type unaryP = func[P any](_ P)
tparam := NewTypeParam(NewTypeName(token.NoPos, nil, "P", nil), &emptyInterface)
params := NewTuple(NewVar(token.NoPos, nil, "_", tparam))
unaryP = NewSignatureType(nil, nil, []*TypeParam{tparam}, params, nil, false)
}
ctxt := NewContext()
// Update the context with an instantiation of nullaryP.
inst := NewSignatureType(nil, nil, nil, nil, nil, false)
if got := ctxt.update("", nullaryP, []Type{Typ[Int]}, inst); got != inst {
t.Error("bad")
}
// unaryP is not identical to nullaryP, so we should not get inst when
// instantiated with identical type arguments.
if got := ctxt.lookup("", unaryP, []Type{Typ[Int]}); got != nil {
t.Error("bad")
}
// nullaryQ is identical to nullaryP, so we *should* get inst when
// instantiated with identical type arguments.
if got := ctxt.lookup("", nullaryQ, []Type{Typ[Int]}); got != inst {
t.Error("bad")
}
// ...but verify we don't get inst with different type arguments.
if got := ctxt.lookup("", nullaryQ, []Type{Typ[String]}); got != nil {
t.Error("bad")
}
}
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