sqlite: fix formatFilepath to handle paths w/wo trailing slash

This adds a a testable helper function to ensure this path construction always remains robust.

pkg/sql/sqlite/connection.go

@@ -83,8 +83,12 @@ func (c *Connection) getFilePath() string {
 	return c.formatFilePath(c.name)
 }
 
+func formatFilePath(path, fileName string) string {
+	return filepath.Join(path, fileName+".sqlite")
+}
+
 func (c *Connection) formatFilePath(fileName string) string {
-	return fmt.Sprintf("%s.sqlite", filepath.Join(c.path, fileName))
+	return formatFilePath(c.path, fileName)
 }
 
 func (c *Connection) openConn() error {

pkg/sql/sqlite/helpers_test.go

@@ -0,0 +1,57 @@
+package sqlite
+
+import (
+	"runtime"
+	"testing"
+)
+
+func Test_formatFilePathNotWindows(t *testing.T) {
+	// This test defines "want" paths in the *NIX path convention used by linux,
+	// mac, bsd, etc., but not windows. Rather than using build flags to skip
+	// this entire file, we'll define this test as such and we can make another
+	// for Windows hosts if we want to.
+	if runtime.GOOS == "windows" {
+		t.Skip("test not applicable to windows paths")
+	}
+	type args struct {
+		path     string
+		fileName string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "abs path no slash",
+			args: args{
+				path:     "/tmp",
+				fileName: "dbname",
+			},
+			want: "/tmp/dbname.sqlite",
+		},
+		{
+			name: "abs path with trailing slash",
+			args: args{
+				path:     "/tmp/",
+				fileName: "dbname",
+			},
+			want: "/tmp/dbname.sqlite",
+		},
+		{
+			name: "rel path no slash",
+			args: args{
+				path:     "./here",
+				fileName: "dbname",
+			},
+			want: "here/dbname.sqlite",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := formatFilePath(tt.args.path, tt.args.fileName); got != tt.want {
+				t.Errorf("formatFilePath() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}