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/engine/kvstore/kvstore.go

@@ -0,0 +1,44 @@
+// Package kvstore contains key-value stores
+package kvstore
+
+import (
+	"errors"
+	"sync"
+)
+
+// MemoryKeyValueStore is an in-memory key-value store
+type MemoryKeyValueStore struct {
+	m  map[string][]byte
+	mu sync.Mutex
+}
+
+// NewMemoryKeyValueStore creates a new in-memory key-value store
+func NewMemoryKeyValueStore() *MemoryKeyValueStore {
+	return &MemoryKeyValueStore{
+		m: make(map[string][]byte),
+	}
+}
+
+// Get returns a key from the key value store
+func (kvs *MemoryKeyValueStore) Get(key string) ([]byte, error) {
+	var (
+		err   error
+		ok    bool
+		value []byte
+	)
+	kvs.mu.Lock()
+	defer kvs.mu.Unlock()
+	value, ok = kvs.m[key]
+	if !ok {
+		err = errors.New("no such key")
+	}
+	return value, err
+}
+
+// Set sets a key into the key value store
+func (kvs *MemoryKeyValueStore) Set(key string, value []byte) error {
+	kvs.mu.Lock()
+	defer kvs.mu.Unlock()
+	kvs.m[key] = value
+	return nil
+}

internal/engine/kvstore/kvstore_test.go

@@ -0,0 +1,28 @@
+package kvstore
+
+import "testing"
+
+func TestNoSuchKey(t *testing.T) {
+	kvs := NewMemoryKeyValueStore()
+	value, err := kvs.Get("nonexistent")
+	if err == nil {
+		t.Fatal("expected an error here")
+	}
+	if value != nil {
+		t.Fatal("expected empty string here")
+	}
+}
+
+func TestExistingKey(t *testing.T) {
+	kvs := NewMemoryKeyValueStore()
+	if err := kvs.Set("antani", []byte("mascetti")); err != nil {
+		t.Fatal(err)
+	}
+	value, err := kvs.Get("antani")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(value) != "mascetti" {
+		t.Fatal("not the result we expected")
+	}
+}