refactor: move more commands to internal/cmd (#207)

* refactor: move more commands to internal/cmd

Part of https://github.com/ooni/probe/issues/1335.

We would like all commands to be at the same level of engine
rather than inside engine (now that we can do it).

* fix: update .gitignore

* refactor: also move jafar outside engine

* We should be good now?

internal/cmd/jafar/main_test.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/ooni/probe-cli/v3/internal/cmd/jafar/iptables"
+	"github.com/ooni/probe-cli/v3/internal/engine/shellx"
+)
+
+func ensureWeStartOverWithIPTables() {
+	iptables.NewCensoringPolicy().Waive()
+}
+
+func TestNoCommand(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("skip test on non Linux systems")
+	}
+	ensureWeStartOverWithIPTables()
+	*dnsProxyAddress = "127.0.0.1:0"
+	*httpProxyAddress = "127.0.0.1:0"
+	*tlsProxyAddress = "127.0.0.1:0"
+	go func() {
+		mainCh <- os.Interrupt
+	}()
+	main()
+}
+
+func TestWithCommand(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("skip test on non Linux systems")
+	}
+	ensureWeStartOverWithIPTables()
+	*dnsProxyAddress = "127.0.0.1:0"
+	*httpProxyAddress = "127.0.0.1:0"
+	*tlsProxyAddress = "127.0.0.1:0"
+	*mainCommand = "whoami"
+	defer func() {
+		*mainCommand = ""
+	}()
+	main()
+}
+
+func TestMustx(t *testing.T) {
+	t.Run("with no error", func(t *testing.T) {
+		var called int
+		mustx(nil, "", func(int) {
+			called++
+		})
+		if called != 0 {
+			t.Fatal("should not happen")
+		}
+	})
+	t.Run("with non-exit-code error", func(t *testing.T) {
+		var (
+			called   int
+			exitcode int
+		)
+		mustx(errors.New("antani"), "", func(ec int) {
+			called++
+			exitcode = ec
+		})
+		if called != 1 {
+			t.Fatal("not called?!")
+		}
+		if exitcode != 1 {
+			t.Fatal("unexpected exitcode value")
+		}
+	})
+	t.Run("with exit-code error", func(t *testing.T) {
+		var (
+			called   int
+			exitcode int
+		)
+		err := shellx.Run("curl", "-sf", "") // cause exitcode == 3
+		mustx(err, "", func(ec int) {
+			called++
+			exitcode = ec
+		})
+		if called != 1 {
+			t.Fatal("not called?!")
+		}
+		if exitcode != 3 {
+			t.Fatal("unexpected exitcode value")
+		}
+	})
+}