Test: Internal exchange coverage (#1525)

* Test: Internal exchange coverage

* Tests: Rename exchange.TestInstance to Setup

This package function is either going to be imported and used as just exchange.Setup,
or more likely testexch.Setup.
This removes the Stutter of having
internal/testing/exchange.TestInstance which is implicit given the
package path

internal/testing/utils/path.go

@@ -0,0 +1,35 @@
+package path
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// Exported public errors
+var (
+	ErrRootNotFound = errors.New("could not find root of gocryptotrader")
+)
+
+// RootPathFromCWD returns the system path to GoCryptoTrader from the current working directory
+// Expects to find LICENSE file
+func RootPathFromCWD() (string, error) {
+	wd, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+	return RootPath(wd)
+}
+
+// RootPath returns the system path to GoCryptoTrader from a sub-directory path
+func RootPath(p string) (string, error) {
+	parts := strings.Split(p, string(filepath.Separator))
+	for i := len(parts); i > 0; i-- {
+		dir := strings.Join(parts[:i], string(filepath.Separator))
+		if _, err := os.Stat(filepath.Join(dir, "LICENSE")); err == nil {
+			return dir, nil
+		}
+	}
+	return "", ErrRootNotFound
+}

internal/testing/utils/path_test.go

@@ -0,0 +1,38 @@
+package path
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestRootPathFromCWD exercises RootPathFromCWD and RootPath
+func TestRootPathFromCWD(t *testing.T) {
+	r, err := RootPathFromCWD()
+	require.NoError(t, err)
+	_, err = os.Stat(filepath.Join(r, "LICENSE"))
+	require.NoError(t, err, "Must find a LICENSE file")
+
+	// Ensure there are no other license files in sub-directories
+	err = filepath.WalkDir(r, func(p string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		// Skip the root of the project
+		w, _ := filepath.Split(p)
+		w = filepath.Clean(w)
+		if w == r {
+			return nil
+		}
+		if d.Type().IsRegular() && d.Name() == "LICENSE" {
+			return fmt.Errorf("found an unexpected LICENSE file in a sub-directory: %s", p)
+		}
+		return nil
+	})
+	assert.NoError(t, err)
+}