Source file src/pkg/cmd/go/internal/test/cover.go

     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 == "" || testC {
    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	}
    85	

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