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      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 // Test2json converts go test output to a machine-readable JSON stream.
      6 //
      7 // Usage:
      8 //
      9 //	go tool test2json [-p pkg] [-t] [./pkg.test -test.v]
     10 //
     11 // Test2json runs the given test command and converts its output to JSON;
     12 // with no command specified, test2json expects test output on standard input.
     13 // It writes a corresponding stream of JSON events to standard output.
     14 // There is no unnecessary input or output buffering, so that
     15 // the JSON stream can be read for live updates of test status.
     16 //
     17 // The -p flag sets the package reported in each test event.
     18 //
     19 // The -t flag requests that time stamps be added to each test event.
     20 //
     21 // Note that test2json is only intended for converting a single test
     22 // binary's output. To convert the output of a "go test" command,
     23 // use "go test -json" instead of invoking test2json directly.
     24 //
     25 // Output Format
     26 //
     27 // The JSON stream is a newline-separated sequence of TestEvent objects
     28 // corresponding to the Go struct:
     29 //
     30 //	type TestEvent struct {
     31 //		Time    time.Time // encodes as an RFC3339-format string
     32 //		Action  string
     33 //		Package string
     34 //		Test    string
     35 //		Elapsed float64 // seconds
     36 //		Output  string
     37 //	}
     38 //
     39 // The Time field holds the time the event happened.
     40 // It is conventionally omitted for cached test results.
     41 //
     42 // The Action field is one of a fixed set of action descriptions:
     43 //
     44 //	run    - the test has started running
     45 //	pause  - the test has been paused
     46 //	cont   - the test has continued running
     47 //	pass   - the test passed
     48 //	bench  - the benchmark printed log output but did not fail
     49 //	fail   - the test or benchmark failed
     50 //	output - the test printed output
     51 //
     52 // The Package field, if present, specifies the package being tested.
     53 // When the go command runs parallel tests in -json mode, events from
     54 // different tests are interlaced; the Package field allows readers to
     55 // separate them.
     56 //
     57 // The Test field, if present, specifies the test, example, or benchmark
     58 // function that caused the event. Events for the overall package test
     59 // do not set Test.
     60 //
     61 // The Elapsed field is set for "pass" and "fail" events. It gives the time
     62 // elapsed for the specific test or the overall package test that passed or failed.
     63 //
     64 // The Output field is set for Action == "output" and is a portion of the test's output
     65 // (standard output and standard error merged together). The output is
     66 // unmodified except that invalid UTF-8 output from a test is coerced
     67 // into valid UTF-8 by use of replacement characters. With that one exception,
     68 // the concatenation of the Output fields of all output events is the exact
     69 // output of the test execution.
     70 //
     71 // When a benchmark runs, it typically produces a single line of output
     72 // giving timing results. That line is reported in an event with Action == "output"
     73 // and no Test field. If a benchmark logs output or reports a failure
     74 // (for example, by using b.Log or b.Error), that extra output is reported
     75 // as a sequence of events with Test set to the benchmark name, terminated
     76 // by a final event with Action == "bench" or "fail".
     77 // Benchmarks have no events with Action == "run", "pause", or "cont".
     78 //
     79 package main
     80 
     81 import (
     82 	"flag"
     83 	"fmt"
     84 	"io"
     85 	"os"
     86 	"os/exec"
     87 
     88 	"cmd/internal/test2json"
     89 )
     90 
     91 var (
     92 	flagP = flag.String("p", "", "report `pkg` as the package being tested in each event")
     93 	flagT = flag.Bool("t", false, "include timestamps in events")
     94 )
     95 
     96 func usage() {
     97 	fmt.Fprintf(os.Stderr, "usage: go tool test2json [-p pkg] [-t] [./pkg.test -test.v]\n")
     98 	os.Exit(2)
     99 }
    100 
    101 func main() {
    102 	flag.Usage = usage
    103 	flag.Parse()
    104 
    105 	var mode test2json.Mode
    106 	if *flagT {
    107 		mode |= test2json.Timestamp
    108 	}
    109 	c := test2json.NewConverter(os.Stdout, *flagP, mode)
    110 	defer c.Close()
    111 
    112 	if flag.NArg() == 0 {
    113 		io.Copy(c, os.Stdin)
    114 	} else {
    115 		args := flag.Args()
    116 		cmd := exec.Command(args[0], args[1:]...)
    117 		w := &countWriter{0, c}
    118 		cmd.Stdout = w
    119 		cmd.Stderr = w
    120 		if err := cmd.Run(); err != nil {
    121 			if w.n > 0 {
    122 				// Assume command printed why it failed.
    123 			} else {
    124 				fmt.Fprintf(c, "test2json: %v\n", err)
    125 			}
    126 			c.Close()
    127 			os.Exit(1)
    128 		}
    129 	}
    130 }
    131 
    132 type countWriter struct {
    133 	n int64
    134 	w io.Writer
    135 }
    136 
    137 func (w *countWriter) Write(b []byte) (int, error) {
    138 	w.n += int64(len(b))
    139 	return w.w.Write(b)
    140 }
    141