refactor(commands): separate commands and its core into two folders (#32)

- I think it would be better if one for commands only, one for the spec
handling core logic so people won't be confused by the core logic inside
the commands folder (cleaner I guess)
- Regen docs

tests/spec/utils_test.go

@@ -0,0 +1,55 @@
+package tests
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/versenilvis/iris/spec"
+)
+
+func TestTokenize(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected []string
+	}{
+		{"Empty input", "", []string{""}},
+		{"Trailing space", "git ", []string{"git", ""}},
+		{"Multi-space", "git  add", []string{"git", "add"}},
+		{"Quoted string", "git commit -m \"hello world\"", []string{"git", "commit", "-m", "hello world"}},
+		{"Quote not closed", "git commit -m \"hello", []string{"git", "commit", "-m", "hello"}},
+		{"Single quote", "git commit -m 'hello world'", []string{"git", "commit", "-m", "hello world"}},
+		{"Backslash escape", "git commit -m \"hello\\ world\"", []string{"git", "commit", "-m", "hello world"}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := spec.Tokenize(tt.input)
+			if !reflect.DeepEqual(got, tt.expected) {
+				t.Errorf("Tokenize(%q) = %v; want %v", tt.input, got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestHasPrefix(t *testing.T) {
+	tests := []struct {
+		name   string
+		s      string
+		prefix string
+		want   bool
+	}{
+		{"Case insensitive", "Hello", "hel", true},
+		{"Unicode support", "Thử nghiệm", "thử", true},
+		{"Prefix longer", "Iris", "Iris-Longer", false},
+		{"Empty prefix", "Iris", "", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := spec.HasPrefix(tt.s, tt.prefix); got != tt.want {
+				t.Errorf("HasPrefix(%q, %q) = %v; want %v", tt.s, tt.prefix, got, tt.want)
+			}
+		})
+	}
+}