github.com/yukk001/go1.10.8@v0.0.0-20190813125351-6df2d3982e20/src/cmd/go/internal/test/cover.go (about)

     1  // Copyright 2017 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 test
     6  
     7  import (
     8  	"cmd/go/internal/base"
     9  	"fmt"
    10  	"io"
    11  	"os"
    12  	"path/filepath"
    13  	"sync"
    14  )
    15  
    16  var coverMerge struct {
    17  	f          *os.File
    18  	sync.Mutex // for f.Write
    19  }
    20  
    21  // initCoverProfile initializes the test coverage profile.
    22  // It must be run before any calls to mergeCoverProfile or closeCoverProfile.
    23  // Using this function clears the profile in case it existed from a previous run,
    24  // or in case it doesn't exist and the test is going to fail to create it (or not run).
    25  func initCoverProfile() {
    26  	if testCoverProfile == "" {
    27  		return
    28  	}
    29  	if !filepath.IsAbs(testCoverProfile) && testOutputDir != "" {
    30  		testCoverProfile = filepath.Join(testOutputDir, testCoverProfile)
    31  	}
    32  
    33  	// No mutex - caller's responsibility to call with no racing goroutines.
    34  	f, err := os.Create(testCoverProfile)
    35  	if err != nil {
    36  		base.Fatalf("%v", err)
    37  	}
    38  	_, err = fmt.Fprintf(f, "mode: %s\n", testCoverMode)
    39  	if err != nil {
    40  		base.Fatalf("%v", err)
    41  	}
    42  	coverMerge.f = f
    43  }
    44  
    45  // mergeCoverProfile merges file into the profile stored in testCoverProfile.
    46  // It prints any errors it encounters to ew.
    47  func mergeCoverProfile(ew io.Writer, file string) {
    48  	if coverMerge.f == nil {
    49  		return
    50  	}
    51  	coverMerge.Lock()
    52  	defer coverMerge.Unlock()
    53  
    54  	expect := fmt.Sprintf("mode: %s\n", testCoverMode)
    55  	buf := make([]byte, len(expect))
    56  	r, err := os.Open(file)
    57  	if err != nil {
    58  		// Test did not create profile, which is OK.
    59  		return
    60  	}
    61  	defer r.Close()
    62  
    63  	n, err := io.ReadFull(r, buf)
    64  	if n == 0 {
    65  		return
    66  	}
    67  	if err != nil || string(buf) != expect {
    68  		fmt.Fprintf(ew, "error: test wrote malformed coverage profile.\n")
    69  		return
    70  	}
    71  	_, err = io.Copy(coverMerge.f, r)
    72  	if err != nil {
    73  		fmt.Fprintf(ew, "error: saving coverage profile: %v\n", err)
    74  	}
    75  }
    76  
    77  func closeCoverProfile() {
    78  	if coverMerge.f == nil {
    79  		return
    80  	}
    81  	if err := coverMerge.f.Close(); err != nil {
    82  		base.Errorf("closing coverage profile: %v", err)
    83  	}
    84  }