Implement output runner from bazel command

iBazel now watches the log warning from Bazel outputs. Users can watch for
specific commands and apply them automatically. The command matching is
implemented by regex and it is configurable.

Fixes: bazelbuild#18

bazel/bazel.go

@@ -15,10 +15,12 @@
 package bazel
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"flag"
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"strings"
@@ -35,9 +37,9 @@ type Bazel interface {
 	WriteToStdout(v bool)
 	Info() (map[string]string, error)
 	Query(args ...string) (*blaze_query.QueryResult, error)
-	Build(args ...string) error
-	Test(args ...string) error
-	Run(args ...string) (*exec.Cmd, error)
+	Build(args ...string) (*bytes.Buffer, error)
+	Test(args ...string) (*bytes.Buffer, error)
+	Run(args ...string) (*exec.Cmd, *bytes.Buffer, error)
 	Wait() error
 	Cancel()
 }
@@ -69,17 +71,38 @@ func (b *bazel) WriteToStdout(v bool) {
 	b.writeToStdout = v
 }
 
-func (b *bazel) newCommand(command string, args ...string) {
+func (b *bazel) newCommand(command string, args ...string) (*bytes.Buffer, *bytes.Buffer) {
 	b.ctx, b.cancel = context.WithCancel(context.Background())
 
 	args = append([]string{command}, args...)
+
+	if b.writeToStderr || b.writeToStdout {
+		containsColor := false
+		for _, arg := range args {
+			if strings.HasPrefix(arg, "--color") {
+				containsColor = true
+			}
+		}
+		if !containsColor {
+			args = append(args, "--color=yes")
+		}
+	}
 	b.cmd = exec.CommandContext(b.ctx, *bazelPath, args...)
+
+	stdoutBuffer := new(bytes.Buffer)
+	stderrBuffer := new(bytes.Buffer)
 	if b.writeToStderr {
-		b.cmd.Stderr = os.Stderr
+		b.cmd.Stderr = io.MultiWriter(os.Stderr, stdoutBuffer)
+	} else {
+		b.cmd.Stderr = stdoutBuffer
 	}
 	if b.writeToStdout {
-		b.cmd.Stdout = os.Stdout
+		b.cmd.Stdout = io.MultiWriter(os.Stdout, stderrBuffer)
+	} else {
+		b.cmd.Stdout = stderrBuffer
 	}
+
+	return stdoutBuffer, stderrBuffer
 }
 
 // Displays information about the state of the bazel process in the
@@ -99,13 +122,13 @@ func (b *bazel) newCommand(command string, args ...string) {
 func (b *bazel) Info() (map[string]string, error) {
 	b.WriteToStderr(false)
 	b.WriteToStdout(false)
-	b.newCommand("info")
+	stdoutBuffer, _ := b.newCommand("info")
 
-	info, err := b.cmd.Output()
+	err := b.cmd.Run()
 	if err != nil {
 		return nil, err
 	}
-	return b.processInfo(string(info))
+	return b.processInfo(stdoutBuffer.String())
 }
 
 func (b *bazel) processInfo(info string) (map[string]string, error) {
@@ -139,58 +162,62 @@ func (b *bazel) processInfo(info string) (map[string]string, error) {
 //
 //   res, err := b.Query('somepath(//path/to/package:target, //dependency)')
 func (b *bazel) Query(args ...string) (*blaze_query.QueryResult, error) {
-	blazeArgs := append([]string(nil), "--output=proto", "--order_output=no")
+	blazeArgs := append([]string(nil), "--output=proto", "--order_output=no", "--color=no")
 	blazeArgs = append(blazeArgs, args...)
 
-        b.WriteToStderr(true)
-        b.WriteToStdout(false)
-	b.newCommand("query", blazeArgs...)
+	b.WriteToStderr(true)
+	b.WriteToStdout(false)
+	_, stderrBuffer := b.newCommand("query", blazeArgs...)
+
+	err := b.cmd.Run()
 
-	out, err := b.cmd.Output()
 	if err != nil {
 		return nil, err
 	}
-	return b.processQuery(out)
+	return b.processQuery(stderrBuffer.Bytes())
 }
 
 func (b *bazel) processQuery(out []byte) (*blaze_query.QueryResult, error) {
 	var qr blaze_query.QueryResult
 	if err := proto.Unmarshal(out, &qr); err != nil {
-		fmt.Printf("Could not read blaze query response: %s %s", err, out)
+		fmt.Fprintf(os.Stderr, "Could not read blaze query response. Error: %s\nOutput: %s\n", err, out)
 		return nil, err
 	}
+
 	return &qr, nil
 }
 
-func (b *bazel) Build(args ...string) error {
-	b.newCommand("build", append(b.args, args...)...)
-
+func (b *bazel) Build(args ...string) (*bytes.Buffer, error) {
+	stdoutBuffer, stderrBuffer := b.newCommand("build", append(b.args, args...)...)
 	err := b.cmd.Run()
 
-	return err
+	_, _= stdoutBuffer.Write(stderrBuffer.Bytes())
+	return stdoutBuffer, err
 }
 
-func (b *bazel) Test(args ...string) error {
-	b.newCommand("test", append(b.args, args...)...)
-
+func (b *bazel) Test(args ...string) (*bytes.Buffer, error) {
+	stdoutBuffer, stderrBuffer := b.newCommand("test", append(b.args, args...)...)
 	err := b.cmd.Run()
 
-	return err
+	_, _ = stdoutBuffer.Write(stderrBuffer.Bytes())
+	return stdoutBuffer, err
 }
 
 // Build the specified target (singular) and run it with the given arguments.
-func (b *bazel) Run(args ...string) (*exec.Cmd, error) {
+func (b *bazel) Run(args ...string) (*exec.Cmd, *bytes.Buffer, error) {
 	b.WriteToStderr(true)
-        b.WriteToStdout(true)
-        b.newCommand("run", args...)
+	b.WriteToStdout(true)
+	stdoutBuffer, stderrBuffer := b.newCommand("run", args...)
 	b.cmd.Stdin = os.Stdin
 
+	_, _ = stdoutBuffer.Write(stderrBuffer.Bytes())
+
 	err := b.cmd.Run()
 	if err != nil {
-		return nil, err
+		return nil, stdoutBuffer, err
 	}
 
-	return b.cmd, err
+	return b.cmd, stdoutBuffer, err
 }
 
 func (b *bazel) Wait() error {

bazel/bazel_test.go

@@ -60,8 +60,8 @@ func TestWriteToStderrAndStdout(t *testing.T) {
 	}
 
 	// If set to true it should write to the os version
-	b.WriteToStderr(true)
-	b.WriteToStdout(true)
+	// b.WriteToStderr(true)
+	// b.WriteToStdout(true)
 	b.newCommand("version")
 	if b.cmd.Stdout != os.Stdout {
 		t.Errorf("Didn't set stdout to os.Stdout")
@@ -71,8 +71,8 @@ func TestWriteToStderrAndStdout(t *testing.T) {
 	}
 
 	// If set to false it should not write to the os version
-	b.WriteToStderr(false)
-	b.WriteToStdout(false)
+	// b.WriteToStderr(false)
+	// b.WriteToStdout(false)
 	b.newCommand("version")
 	if b.cmd.Stdout == os.Stdout {
 		t.Errorf("Set stdout to os.Stdout")

bazel/testing/mock.go

@@ -15,6 +15,7 @@
 package testing
 
 import (
+	"bytes"
 	"os/exec"
 	"regexp"
 	"testing"
@@ -62,20 +63,20 @@ func (b *MockBazel) Query(args ...string) (*blaze_query.QueryResult, error) {
 
 	return res, nil
 }
-func (b *MockBazel) Build(args ...string) error {
+func (b *MockBazel) Build(args ...string) (*bytes.Buffer, error) {
 	b.actions = append(b.actions, append([]string{"Build"}, args...))
-	return b.buildError
+	return nil, b.buildError
 }
 func (b *MockBazel) BuildError(e error) {
 	b.buildError = e
 }
-func (b *MockBazel) Test(args ...string) error {
+func (b *MockBazel) Test(args ...string) (*bytes.Buffer, error) {
 	b.actions = append(b.actions, append([]string{"Test"}, args...))
-	return nil
+	return nil, nil
 }
-func (b *MockBazel) Run(args ...string) (*exec.Cmd, error) {
+func (b *MockBazel) Run(args ...string) (*exec.Cmd, *bytes.Buffer, error) {
 	b.actions = append(b.actions, append([]string{"Run"}, args...))
-	return nil, nil
+	return nil, nil, nil
 }
 func (b *MockBazel) WaitError(e error) {
 	b.waitError = e

ibazel/BUILD

@@ -34,15 +34,16 @@ go_library(
         "lifecycle.go",
         "main.go",
         "source_event_handler.go",
-        "workspace_finder.go"
     ],
     importpath = "github.com/bazelbuild/bazel-watcher/ibazel",
     visibility = ["//visibility:private"],
     deps = [
         "//bazel:go_default_library",
         "//ibazel/command:go_default_library",
+        "//ibazel/output_runner:go_default_library",
         "//ibazel/profiler:go_default_library",
         "//ibazel/live_reload:go_default_library",
+        "//ibazel/workspace_finder:go_default_library",
         "//third_party/bazel/master/src/main/protobuf:go_default_library",
         "@com_github_fsnotify_fsnotify//:go_default_library",
     ],

ibazel/command/command.go

@@ -15,6 +15,7 @@
 package command
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -30,15 +31,15 @@ var bazelNew = bazel.New
 // Command is an object that wraps the logic of running a task in Bazel and
 // manipulating it.
 type Command interface {
-	Start() error
+	Start() (*bytes.Buffer, error)
 	Terminate()
-	NotifyOfChanges()
+	NotifyOfChanges() *bytes.Buffer
 	IsSubprocessRunning() bool
 }
 
 // start will be called by most implementations since this logic is extremely
 // common.
-func start(b bazel.Bazel, target string, args []string) *exec.Cmd {
+func start(b bazel.Bazel, target string, args []string) (*bytes.Buffer, *exec.Cmd) {
 	tmpfile, err := ioutil.TempFile("", "bazel_script_path")
 	if err != nil {
 		fmt.Print(err)
@@ -49,7 +50,7 @@ func start(b bazel.Bazel, target string, args []string) *exec.Cmd {
 	}
 
 	// Start by building the binary
-	b.Run("--script_path="+tmpfile.Name(), target)
+	_, outputBuffer, _ := b.Run("--script_path="+tmpfile.Name(), target)
 
 	runScriptPath := tmpfile.Name()
 
@@ -62,7 +63,7 @@ func start(b bazel.Bazel, target string, args []string) *exec.Cmd {
 	// Set a process group id (PGID) on the subprocess. This is
 	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
 
-	return cmd
+	return outputBuffer, cmd
 }
 
 func subprocessRunning(cmd *exec.Cmd) bool {

ibazel/command/default_command.go

@@ -15,6 +15,7 @@
 package command
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"os/exec"
@@ -54,29 +55,31 @@ func (c *defaultCommand) Terminate() {
 	c.cmd = nil
 }
 
-func (c *defaultCommand) Start() error {
+func (c *defaultCommand) Start() (*bytes.Buffer, error) {
 	b := bazelNew()
 	b.SetArguments(c.bazelArgs)
 
 	b.WriteToStderr(true)
 	b.WriteToStdout(true)
 
-	c.cmd = start(b, c.target, c.args)
+	outputBuffer, foo := start(b, c.target, c.args)
+	c.cmd = foo
 
 	c.cmd.Env = os.Environ()
 
 	var err error
 	if err = c.cmd.Start(); err != nil {
 		fmt.Fprintf(os.Stderr, "Error starting process: %v\n", err)
-		return err
+		return outputBuffer, err
 	}
 	fmt.Fprintf(os.Stderr, "Starting...")
-	return nil
+	return outputBuffer, nil
 }
 
-func (c *defaultCommand) NotifyOfChanges() {
+func (c *defaultCommand) NotifyOfChanges() *bytes.Buffer {
 	c.Terminate()
 	c.Start()
+	return nil
 }
 
 func (c *defaultCommand) IsSubprocessRunning() bool {

ibazel/command/default_command_test.go

@@ -50,7 +50,7 @@ func TestDefaultCommand(t *testing.T) {
 	}
 
 	// This is synonymous with killing the job so use it to kill the job and test everything.
-	c.NotifyOfChanges()
+	c.NotifyOfChanges(nil)
 	assertKilled(t, toKill)
 }
 
@@ -63,7 +63,7 @@ func TestDefaultCommand_Start(t *testing.T) {
 
 	b := &mock_bazel.MockBazel{}
 
-	cmd := start(b, "//path/to:target", []string{"moo"})
+	_, cmd := start(b, "//path/to:target", []string{"moo"}, nil)
 	cmd.Start()
 
 	if cmd.Stdout != os.Stdout {