Source file src/testing/run_example_js.go

     1	// Copyright 2019 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	// +build js
     6	
     7	package testing
     8	
     9	import (
    10		"fmt"
    11		"io"
    12		"os"
    13		"strings"
    14		"time"
    15	)
    16	
    17	// TODO(@musiol, @odeke-em): unify this code back into
    18	// example.go when js/wasm gets an os.Pipe implementation.
    19	func runExample(eg InternalExample) (ok bool) {
    20		if *chatty {
    21			fmt.Printf("=== RUN   %s\n", eg.Name)
    22		}
    23	
    24		// Capture stdout to temporary file. We're not using
    25		// os.Pipe because it is not supported on js/wasm.
    26		stdout := os.Stdout
    27		f := createTempFile(eg.Name)
    28		os.Stdout = f
    29		start := time.Now()
    30	
    31		// Clean up in a deferred call so we can recover if the example panics.
    32		defer func() {
    33			timeSpent := time.Since(start)
    34	
    35			// Restore stdout, get output and remove temporary file.
    36			os.Stdout = stdout
    37			var buf strings.Builder
    38			_, seekErr := f.Seek(0, os.SEEK_SET)
    39			_, readErr := io.Copy(&buf, f)
    40			out := buf.String()
    41			f.Close()
    42			os.Remove(f.Name())
    43			if seekErr != nil {
    44				fmt.Fprintf(os.Stderr, "testing: seek temp file: %v\n", seekErr)
    45				os.Exit(1)
    46			}
    47			if readErr != nil {
    48				fmt.Fprintf(os.Stderr, "testing: read temp file: %v\n", readErr)
    49				os.Exit(1)
    50			}
    51	
    52			err := recover()
    53			ok = eg.processRunResult(out, timeSpent, err)
    54		}()
    55	
    56		// Run example.
    57		eg.F()
    58		return
    59	}
    60	
    61	func createTempFile(exampleName string) *os.File {
    62		for i := 0; ; i++ {
    63			name := fmt.Sprintf("%s/go-example-stdout-%s-%d.txt", os.TempDir(), exampleName, i)
    64			f, err := os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
    65			if err != nil {
    66				if os.IsExist(err) {
    67					continue
    68				}
    69				fmt.Fprintf(os.Stderr, "testing: open temp file: %v\n", err)
    70				os.Exit(1)
    71			}
    72			return f
    73		}
    74	}
    75	

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