Тесты проходят. Теперь бы линтеры победить..

hw02_unpack_string/go.mod

@@ -1,4 +1,4 @@
-module github.com/fixme_my_friend/hw02_unpack_string
+module github.com/tiburon-777/hw02_unpack_string
 
 go 1.14
 

hw02_unpack_string/unpack.go

@@ -2,11 +2,59 @@ package hw02_unpack_string //nolint:golint,stylecheck
 
 import (
 	"errors"
+	"strconv"
+	"strings"
+	"unicode"
 )
 
 var ErrInvalidString = errors.New("invalid string")
 
-func Unpack(_ string) (string, error) {
-	// Place your code here
-	return "", nil
+const slash = `\`
+
+func Unpack(str string) (string, error) {
+	var b strings.Builder
+	temp := []rune(str)
+	for i := 0; i < len(temp); i++ {
+		if unicode.IsLetter(temp[i]) {
+			// Ловим паттерн [letter][digit]
+			if i < len(temp)-1 && unicode.IsDigit(temp[i+1]) {
+				c, err := strconv.Atoi(string(temp[i+1]))
+				if err != nil {
+					return "", err
+				}
+				b.WriteString(strings.Repeat(string(temp[i]), c))
+				i++
+				// Ловим паттерн [letter]...
+			} else {
+				b.WriteRune(temp[i])
+			}
+		} else if string(temp[i]) == slash {
+			// Ловим паттерн [\][letter][digit]
+			if i < len(temp)-2 && unicode.IsLetter(temp[i+1]) && unicode.IsDigit(temp[i+2]) {
+				c, err := strconv.Atoi(string(temp[i+2]))
+				if err != nil {
+					return "", err
+				}
+				b.WriteString(strings.Repeat(slash+string(temp[i+1]), c))
+				i += 2
+				// Ловим паттерн [\][digit или \][digit]
+			} else if i < len(temp)-2 && (unicode.IsDigit(temp[i+1]) || string(temp[i+1]) == slash) && unicode.IsDigit(temp[i+2]) {
+				c, err := strconv.Atoi(string(temp[i+2]))
+				if err != nil {
+					return "", err
+				}
+				b.WriteString(strings.Repeat(string(temp[i+1]), c))
+				i += 2
+				// Ловим паттерн [\][digit или \]
+			} else if i < len(temp)-1 && (unicode.IsDigit(temp[i+1]) || string(temp[i+1]) == slash) {
+				b.WriteRune(temp[i+1])
+				i++
+			} else {
+				return "", ErrInvalidString
+			}
+		} else {
+			return "", ErrInvalidString
+		}
+	}
+	return b.String(), nil
 }

hw02_unpack_string/unpack_test.go

@@ -45,6 +45,29 @@ func TestUnpack(t *testing.T) {
 			input:    "aaa0b",
 			expected: "aab",
 		},
+		{
+			input:    "fftcwerv ervev sva5scs",
+			expected: "",
+			err:      ErrInvalidString,
+		},
+		{
+			input:    `||\||(8^`,
+			expected: "",
+			err:      ErrInvalidString,
+		},
+		{
+			input:    "ис3куРАкс2еу",
+			expected: "иссскуРАкссеу",
+		},
+		{
+			input:    "рлрплотчрв",
+			expected: "рлрплотчрв",
+		},
+		{
+			input:    string([]rune{1234, 67, 45, 2324, 899, 353, 2345, 65}),
+			expected: "",
+			err:      ErrInvalidString,
+		},
 	} {
 		result, err := Unpack(tst.input)
 		require.Equal(t, tst.err, err)
@@ -53,7 +76,7 @@ func TestUnpack(t *testing.T) {
 }
 
 func TestUnpackWithEscape(t *testing.T) {
-	t.Skip() // Remove if task with asterisk completed
+	//t.Skip() // Remove if task with asterisk completed
 
 	for _, tst := range [...]test{
 		{
@@ -72,6 +95,11 @@ func TestUnpackWithEscape(t *testing.T) {
 			input:    `qwe\\\3`,
 			expected: `qwe\3`,
 		},
+		{
+			input:    `3\\cds\4`,
+			expected: ``,
+			err:      ErrInvalidString,
+		},
 	} {
 		result, err := Unpack(tst.input)
 		require.Equal(t, tst.err, err)