stdlib_test.go

Documentation: golang.org/x/tools/go/packages

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package packages_test
     6  
     7  import (
     8  	"runtime"
     9  	"testing"
    10  	"time"
    11  
    12  	"golang.org/x/tools/go/packages"
    13  	"golang.org/x/tools/internal/testenv"
    14  )
    15  
    16  // This test loads the metadata for the standard library,
    17  func TestStdlibMetadata(t *testing.T) {
    18  	testenv.NeedsGoPackages(t)
    19  
    20  	runtime.GC()
    21  	t0 := time.Now()
    22  	var memstats runtime.MemStats
    23  	runtime.ReadMemStats(&memstats)
    24  	alloc := memstats.Alloc
    25  
    26  	// Load, parse and type-check the program.
    27  	cfg := &packages.Config{Mode: packages.LoadAllSyntax}
    28  	pkgs, err := packages.Load(cfg, "std")
    29  	if err != nil {
    30  		t.Fatalf("failed to load metadata: %v", err)
    31  	}
    32  	if packages.PrintErrors(pkgs) > 0 {
    33  		t.Fatal("there were errors loading standard library")
    34  	}
    35  
    36  	t1 := time.Now()
    37  	runtime.GC()
    38  	runtime.ReadMemStats(&memstats)
    39  	runtime.KeepAlive(pkgs)
    40  
    41  	t.Logf("Loaded %d packages", len(pkgs))
    42  	numPkgs := len(pkgs)
    43  
    44  	want := 150 // 186 on linux, 185 on windows.
    45  	if numPkgs < want {
    46  		t.Errorf("Loaded only %d packages, want at least %d", numPkgs, want)
    47  	}
    48  
    49  	t.Log("GOMAXPROCS: ", runtime.GOMAXPROCS(0))
    50  	t.Log("Metadata:   ", t1.Sub(t0))                          // ~800ms on 12 threads
    51  	t.Log("#MB:        ", int64(memstats.Alloc-alloc)/1000000) // ~1MB
    52  }
    53
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