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// Copyright 2025 The Tessera authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package tessera
import (
"context"
"testing"
)
func TestMemoize(t *testing.T) {
// Set up an AddFn which will increment a counter every time it's called, and return that in the Index.
i := uint64(0)
deleg := func() (Index, error) {
i++
return Index{
Index: i,
}, nil
}
add := func(_ context.Context, _ *Entry) IndexFuture {
return deleg
}
// Create a single future (for a single Entry), and convince ourselves that the counter is being incremented
// each time the future is being invoked.
f1 := add(nil, nil)
a, _ := f1()
b, _ := f1()
if a.Index == b.Index {
t.Fatalf("a(=%d) == b(=%d)", a.Index, b.Index)
}
// Now create an AddFn which memoizes the result of the delegate, like we do in NewAppender, and assert that
// repeated calls to the future work as expected; only incrementing the counter once.
add = func(_ context.Context, _ *Entry) IndexFuture {
return memoizeFuture(deleg)
}
f2 := add(nil, nil)
c, _ := f2()
d, _ := f2()
if c.Index != d.Index {
t.Fatalf("c(=%d) != d(=%d)", c.Index, d.Index)
}
}
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