#1 MVP has been baked.

README.md

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+# scm 💪
+
+---
+
+## It's time 🕒 to clone ⤵️ interesting 🧐 repo faster ⏩ and cleaner 🧹
+
+![Usage example](demo.svg)
+
+Just type:
+
+```shell
+scm https://github.com/pkorobeinikov/scm
+```
+
+It will clone `https://github.com/pkorobeinikov/scm` into `~/Workspace/github.com/pkorobeinikov/scm`.
+
+It's also possible to clone `hg`-repo. So command:
+
+```shell
+scm hg http://hg.nginx.org/nginx
+```
+
+will clone `scm hg http://hg.nginx.org/nginx/` into `~/Workspace/hg.nginx.org/nginx`.
+
+## Configuration
+
+Put this into your `.rc`-file:
+
+```shell
+export SCM_WORKSPACE_DIR="~/Projects"         # defaults to ~/Workspace
+export SCM_WORKSPACE_DIR_DEFAULT_PERM="0755"  # defaults to 0755
+```
+
+## Building from source
+
+```shell
+go build -o ~/Bin/scm main.go
+```
+
+## Running tests
+
+```shell
+ go test  -cover -v ./internal
+```

go.mod

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+module scm
+
+go 1.15

internal/args.go

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+package internal
+
+import (
+	"errors"
+)
+
+func ParseArgs(args []string) (scmBin, scmUrl string, err error) {
+	switch len(args) {
+	default:
+		err = TooLongArgumentListErr
+		return
+	case 1:
+		err = NotEnoughArgumentsErr
+		return
+	case 2:
+		scmBin = "git"
+		scmUrl = args[1]
+		return
+	case 3:
+		scmBin = args[1]
+		scmUrl = args[2]
+		return
+	}
+}
+
+var (
+	NotEnoughArgumentsErr  = errors.New(`need at least one argument with repo url`)
+	TooLongArgumentListErr = errors.New(`too long argument list`)
+)

internal/args_test.go

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+package internal
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestParseArgs(t *testing.T) {
+	t.Run(`complex`, func(t *testing.T) {
+		testCases := []struct {
+			name     string
+			given    []string
+			expected struct {
+				scmBin string
+				scmUrl string
+				err    error
+			}
+		}{
+			{
+				name:  "not enough arguments",
+				given: []string{"scm"},
+				expected: struct {
+					scmBin string
+					scmUrl string
+					err    error
+				}{
+					scmBin: "",
+					scmUrl: "",
+					err:    NotEnoughArgumentsErr,
+				},
+			},
+			{
+				name:  "too long argument list",
+				given: []string{"foo", "bar", "baz", "quix"},
+				expected: struct {
+					scmBin string
+					scmUrl string
+					err    error
+				}{
+					scmBin: "",
+					scmUrl: "",
+					err:    TooLongArgumentListErr,
+				},
+			},
+			{
+				name:  "git by default",
+				given: []string{"scm", "https://github.com/user/repo"},
+				expected: struct {
+					scmBin string
+					scmUrl string
+					err    error
+				}{
+					scmBin: "git",
+					scmUrl: "https://github.com/user/repo",
+					err:    nil,
+				},
+			},
+			{
+				name:  "hg if needed",
+				given: []string{"scm", "hg", "http://hg.robustwebserver.org/robustwebserver/"},
+				expected: struct {
+					scmBin string
+					scmUrl string
+					err    error
+				}{
+					scmBin: "hg",
+					scmUrl: "http://hg.robustwebserver.org/robustwebserver/",
+					err:    nil,
+				},
+			},
+		}
+
+		for _, testCase := range testCases {
+			t.Run(fmt.Sprintf("%s", testCase.name), func(t *testing.T) {
+				actualScmBin, actualScmUrl, actualErr := ParseArgs(testCase.given)
+
+				if testCase.expected.scmBin != actualScmBin {
+					t.Fail()
+				}
+
+				if testCase.expected.scmUrl != actualScmUrl {
+					t.Fail()
+				}
+
+				if testCase.expected.err != actualErr {
+					t.Fail()
+				}
+			})
+		}
+	})
+}

internal/cfg.go

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+package internal
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+)
+
+type Cfg struct {
+	ScmWorkspaceDirDefaultPerm os.FileMode
+	ScmWorkingCopyPath         string
+}
+
+func ReadCfg(scmUrl string) (Cfg, error) {
+	scmWorkspaceDir := LookupEnvOrDefault("SCM_WORKSPACE_DIR", "~/Workspace")
+	scmExpanedWorkspaceDir, err := ExpandHomeDir(scmWorkspaceDir)
+	if err != nil {
+		return Cfg{}, err
+	}
+
+	scmWorkspaceDirDefaultPermStr := LookupEnvOrDefault("SCM_WORKSPACE_DIR_DEFAULT_PERM", "0755")
+	scmWorkspaceDirDefaultPerm, err := strconv.ParseInt(scmWorkspaceDirDefaultPermStr, 8, strconv.IntSize)
+	scmWorkspaceDirDefaultPermFileMode := os.FileMode(scmWorkspaceDirDefaultPerm)
+
+	scmPathFromUrl, err := ExtractLocalPathFromScmURL(scmUrl)
+	if err != nil {
+		return Cfg{}, err
+	}
+	scmWorkingCopyPath := filepath.Join(scmExpanedWorkspaceDir, scmPathFromUrl)
+
+	return Cfg{
+		ScmWorkspaceDirDefaultPerm: scmWorkspaceDirDefaultPermFileMode,
+		ScmWorkingCopyPath:         scmWorkingCopyPath,
+	}, nil
+}

internal/cfg_test.go

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+package internal
+
+import (
+	"os"
+	"testing"
+)
+
+func TestReadCfg(t *testing.T) {
+	t.Run(`positive`, func(t *testing.T) {
+		saveScmWorkspaceDir := os.Getenv(`SCM_WORKSPACE_DIR`)
+
+		expected := Cfg{
+			ScmWorkspaceDirDefaultPerm: 0755,
+			ScmWorkingCopyPath:         `/tmp/Workspace/github.com/user/repo`,
+		}
+
+		_ = os.Setenv(`SCM_WORKSPACE_DIR`, `/tmp/Workspace`)
+		actual, _ := ReadCfg(`https://github.com/user/repo`)
+
+		if expected.ScmWorkspaceDirDefaultPerm != actual.ScmWorkspaceDirDefaultPerm {
+			t.Errorf(`want "%s", got "%s"`, expected.ScmWorkspaceDirDefaultPerm, actual.ScmWorkspaceDirDefaultPerm)
+		}
+
+		if expected.ScmWorkingCopyPath != actual.ScmWorkingCopyPath {
+			t.Errorf(`want "%s", got "%s"`, expected.ScmWorkingCopyPath, actual.ScmWorkingCopyPath)
+		}
+
+		_ = os.Setenv(`SCM_WORKSPACE_DIR`, saveScmWorkspaceDir)
+	})
+
+	t.Run(`homedir not detected`, func(t *testing.T) {
+		saveScmWorkspaceDir := os.Getenv(`SCM_WORKSPACE_DIR`)
+		saveHome := os.Getenv(`HOME`)
+
+		_ = os.Unsetenv(`HOME`)
+		_ = os.Setenv(`SCM_WORKSPACE_DIR`, `~/Workspace`)
+		_, err := ReadCfg(`https://github.com/user/repo`)
+		if err == nil {
+			t.Errorf(`homedir detected but shouldn't'`)
+		}
+
+		_ = os.Setenv(`HOME`, saveHome)
+		_ = os.Setenv(`SCM_WORKSPACE_DIR`, saveScmWorkspaceDir)
+	})
+
+	t.Run(`mailformed repo url given`, func(t *testing.T) {
+		_, err := ReadCfg(`https://github % com/user/repo`)
+		if err == nil {
+			t.Errorf(`repo url parsed but shouldn't'`)
+		}
+	})
+}

internal/clone.go

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+package internal
+
+import (
+	"os"
+	"os/exec"
+)
+
+func PrepareLocalWorkingCopyPath(scmWorkingCopyPath string, scmWorkspaceDirDefaultPermFileMode os.FileMode) error {
+	return os.MkdirAll(scmWorkingCopyPath, scmWorkspaceDirDefaultPermFileMode)
+}
+
+func Clone(scmBin, scmUrl, scmWorkingCopyPath string) error {
+	scmCmd := exec.Command(scmBin, "clone", scmUrl, scmWorkingCopyPath)
+	scmCmd.Stdout = os.Stdout
+	scmCmd.Stderr = os.Stderr
+
+	if err := scmCmd.Run(); err != nil {
+		return err
+	}
+
+	return nil
+}

internal/clone_test.go

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+package internal
+
+import (
+	"os"
+	"testing"
+)
+
+func TestPrepareLocalWorkingCopyPath(t *testing.T) {
+	t.Run(`positive`, func(t *testing.T) {
+		err := PrepareLocalWorkingCopyPath(`/tmp/Workspace/foobar`, 0755)
+		if err != nil {
+			t.Error(`expected to create workspace directory without any errors`)
+		}
+	})
+}
+
+func TestClone(t *testing.T) {
+	t.Run(`positive`, func(t *testing.T) {
+		dest := `/tmp/github/gitignore`
+
+		err := Clone(`git`, `https://github.com/github/gitignore`, dest)
+		if err != nil {
+			t.Error(`expected to clone repo without any errors`)
+		}
+
+		_ = os.RemoveAll(dest)
+	})
+
+	t.Run(`negative`, func(t *testing.T) {
+		err := Clone(`unknown-scm`, `https://github.com/github/gitignore`, `/tmp/github/gitignore`)
+		if err == nil {
+			t.Error(`expected to fail with unknown command`)
+		}
+	})
+}

internal/homedir.go

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+package internal
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func ExpandHomeDir(d string) (string, error) {
+	if strings.HasPrefix(d, `~/`) {
+		homeDir, err := os.UserHomeDir()
+		if err != nil {
+			return "", err
+		}
+
+		return filepath.Join(homeDir, d[2:]), nil
+	}
+
+	return d, nil
+}

internal/homedir_test.go

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+package internal
+
+import (
+	"os"
+	"testing"
+)
+
+func TestExpandHomeDir(t *testing.T) {
+	t.Run(`positive`, func(t *testing.T) {
+		actual, _ := ExpandHomeDir(`~/Workspace`)
+		// fixme hardcoded value
+		if `/Users/pkorobeinikov/Workspace` != actual {
+			t.Fail()
+		}
+	})
+
+	t.Run(`no home dir in path`, func(t *testing.T) {
+		actual, _ := ExpandHomeDir(`/mnt/Volumes/Workspace`)
+		if `/mnt/Volumes/Workspace` != actual {
+			t.Fail()
+		}
+	})
+
+	t.Run(`homedir not set`, func(t *testing.T) {
+		saveHome := os.Getenv(`HOME`)
+
+		_ = os.Unsetenv(`HOME`)
+		_, err := ExpandHomeDir(`~/Workspace`)
+		if err == nil {
+			t.Fail()
+		}
+
+		_ = os.Setenv(`HOME`, saveHome)
+	})
+}

internal/lookup.go

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+package internal
+
+import "os"
+
+func LookupEnvOrDefault(envName, defaultValue string) string {
+	if value, found := os.LookupEnv(envName); found {
+		return value
+	} else {
+		return defaultValue
+	}
+}