Improve parser. Add more tests.

* src/cf.c: New global option "expand-undefined".
(global_attrib_set): Handle the 'b' data type marker.
* src/cf.h (expand_undefined): New extern.
* src/cfgram.y: Provide textual descriptions for named tokens.
Require '=' or '=~' between identifier and value in SET and SETENV
rules. Allow for values in UNSETENV list.
* src/cflex.l: Accept slashes in unquoted strings.
Gracefully handle undefined escape sequences in strings.
* src/map.c (expand_undefined): New global.
(rush_expand_string): Expand undefined variables to empty strings
if expand_undefined is set.
* tests/Makefile.am: Add new tests.
* tests/testsuite.at: Add new tests.
* tests/backref.at: New file.
* tests/clrenv.at: New file.
* tests/keepenv.at: New file.
* tests/regexp.at: New file.
* tests/setenv.at: New file.
* tests/setvar.at: New file.
* tests/undef.at: New file.

19 files changed, 723 insertions, 71 deletions

diff --git a/src/cf.c b/src/cf.c
index 2742fa7..e304be9 100644
--- a/src/cf.c
+++ b/src/cf.c
@@ -862,6 +862,13 @@ glattrib_acct_umask(int argc, struct argval *arg)
 	return parse_file_mode(arg->strval, &rushdb_umask, &arg->loc);
 }
 
+static int
+glattrib_expand_undef(int argc, struct argval *arg)
+{
+	expand_undefined = arg->intval;
+	return 0;
+}
+
 static struct global_attrib global_attrib[] = {
 	{ "debug",            "n",  glattrib_debug },
 	{ "sleep-time",       "n",  glattrib_sleep_time },
@@ -871,6 +878,7 @@ static struct global_attrib global_attrib[] = {
 	{ "acct-file-mode",   "s",  glattrib_acct_file_mode },
 	{ "acct-dir-mode",    "s",  glattrib_acct_dir_mode },
 	{ "acct-umask",       "s",  glattrib_acct_umask },
+	{ "expand-undefined", "b",  glattrib_expand_undef },
 	{ NULL }
 };
 
@@ -906,6 +914,15 @@ global_attrib_set(struct global_attrib *glatt,
 		case 's':
 			i++;
 			break;
+		case 'b':
+			if (get_bool(arg->strval, &arg->intval)) {
+				cferror(loc,
+					_("expected boolean value, but found `%s'"),
+					arg->strval);
+				return 1;
+			}
+			i++;
+			break;
 		case '.':
 			break;
 		case 0:
diff --git a/src/cf.h b/src/cf.h
index 5e3b2d2..4ba1800 100644
--- a/src/cf.h
+++ b/src/cf.h
@@ -152,6 +152,7 @@ void global_attrib_set(struct global_attrib *glatt,
 
 
 extern int re_flags;
+extern int expand_undefined;
 extern struct cfloc curloc;
 
 void trimws(char *s);
diff --git a/src/cfgram.y b/src/cfgram.y
index 052dae6..386608f 100644
--- a/src/cfgram.y
+++ b/src/cfgram.y
@@ -1,4 +1,4 @@
-/* This file is part of GNU Rush.                  
+/* This file is part of GNU Rush.
    Copyright (C) 2008-2019 Sergey Poznyakoff
 
    GNU Rush is free software; you can redistribute it and/or modify
@@ -20,11 +20,12 @@
 static int errors;
 int re_flags = REG_EXTENDED;
 static struct rush_rule *current_rule;
-struct name_entry {
-	struct name_entry *next;
+struct asgn {
+	struct asgn *next;
 	char *name;
+	char *value;
 };
-static void add_name_list(struct name_entry *head, enum envar_type type);
+static void add_asgn_list(struct asgn *head, enum envar_type type);
 %}
 
 %error-verbose
@@ -45,10 +46,11 @@ static void add_name_list(struct name_entry *head, enum envar_type type);
 		int start;
 		int end;
 	} range;
+	struct asgn *asgn;
 	struct {
-		struct name_entry *head;
-		struct name_entry *tail;
-	} name_list;
+		struct asgn *head;
+		struct asgn *tail;
+	} asgn_list;
 	struct limits_rec *lrec;
 	rule_attrib_setter_t attrib;
 	struct global_attrib *global_attrib;
@@ -85,10 +87,23 @@ static void add_name_list(struct name_entry *head, enum envar_type type);
 %token <global_attrib> GLATTRIB "global attribute"
 %token BOGUS "erroneous token"
 
+%token OR "||"
+%token AND "&&"
+%token NOT "!"
+%token EQ "=="
+%token NE "!="
+%token LT "<"
+%token LE "<="
+%token GT ">"
+%token GE ">="
+%token XF "=~"
+%token IN "in"
+%token MEMBER "member"
+
 %left OR
 %left AND
 %left NOT
-%nonassoc EQ NE LT LE GT GE '~' IN MEMBER
+%nonassoc EQ NE LT LE GT GE XF '~' IN MEMBER
 
 %type <intval> fdescr index
 %type <str> literal string value defval ruleid
@@ -96,18 +111,19 @@ static void add_name_list(struct name_entry *head, enum envar_type type);
 %type <node> expr compound_cond simple_cond
 %type <range> range
 %type <lrec> resource_limits
-%type <name_list> name_list
+%type <asgn> asgn
+%type <asgn_list> asgn_list
 %type <strlist> strlist
 %type <arg> arg
 %type <arglist> arglist
 
 %%
 rcfile     : PREFACE EOL content
-             {
+	     {
 		     if (errors)
 			     YYERROR;
 	     }
-           | BOGUS
+	   | BOGUS
 	     {
 		     if (parse_old_rc())
 			     YYERROR;
@@ -115,11 +131,11 @@ rcfile     : PREFACE EOL content
 	   ;
 
 content    : /* empty */
-           | rulelist
-           ;
+	   | rulelist
+	   ;
 
 rulelist   : rule
- 	   | rulelist rule
+	   | rulelist rule
 	   ;
 
 rule       : rulehdr rulebody
@@ -183,10 +199,10 @@ rulehdr    : RULE ruleid EOL
 	   ;
 
 ruleid     : /* empty */
-             {
+	     {
 		     $$ = NULL;
 	     }
-           | string
+	   | string
 	   ;
 
 rulebody   : stmt
@@ -202,8 +218,8 @@ stmt       : match_stmt EOL
 	   | include_stmt EOL
 	   | flowctl_stmt EOL
 	   | attrib_stmt EOL
-           | error { skiptoeol(); } EOL
-             {
+	   | error { skiptoeol(); } EOL
+	     {
 		     restorenormal();
 		     yyerrok;
 		     yyclearin;
@@ -356,17 +372,17 @@ regex      : string
 /* ******************
    Set statement
    ****************** */
-set_stmt   : SET index value
+set_stmt   : SET index '=' value
 	     {
 		     struct transform_node *node;
 
 		     node = new_transform_node(current_rule, transform_set);
 		     node->target.type = target_arg;
 		     node->target.v.arg = $2;
-		     node->v.xf.pattern = $3;
+		     node->v.xf.pattern = $4;
 		     node->v.xf.trans = NULL;
 	     }
-	   | SET index '~' value
+	   | SET index XF value
 	     {
 		     struct transform_node *node;
 
@@ -376,17 +392,17 @@ set_stmt   : SET index value
 		     node->v.xf.pattern = NULL;
 		     node->v.xf.trans = compile_transform_expr($4, re_flags);
 	     }
-	   | SET index string '~' value
+	   | SET index '=' string '~' value
 	     {
 		     struct transform_node *node;
 
 		     node = new_transform_node(current_rule, transform_set);
 		     node->target.type = target_arg;
 		     node->target.v.arg = $2;
-		     node->v.xf.pattern = $3;
-		     node->v.xf.trans = compile_transform_expr($5, re_flags);
+		     node->v.xf.pattern = $4;
+		     node->v.xf.trans = compile_transform_expr($6, re_flags);
 	     }
-	   | SET IDENT value
+	   | SET IDENT '=' value
 	     {
 		     struct transform_node *node;
 
@@ -401,10 +417,10 @@ set_stmt   : SET index value
 			     node->target.type = target_var;
 			     node->target.v.name = $2;
 		     }
-		     node->v.xf.pattern = $3;
+		     node->v.xf.pattern = $4;
 		     node->v.xf.trans = NULL;
 	     }
-	   | SET IDENT '~' value
+	   | SET IDENT XF value
 	     {
 		     struct transform_node *node;
 
@@ -422,7 +438,7 @@ set_stmt   : SET index value
 		     node->v.xf.pattern = NULL;
 		     node->v.xf.trans = compile_transform_expr($4, re_flags);
 	     }
-	   | SET IDENT string '~' value
+	   | SET IDENT '=' string '~' value
 	     {
 		     struct transform_node *node;
 
@@ -437,8 +453,8 @@ set_stmt   : SET index value
 			     node->target.type = target_var;
 			     node->target.v.name = $2;
 		     }
-		     node->v.xf.pattern = $3;
-		     node->v.xf.trans = compile_transform_expr($5, re_flags);
+		     node->v.xf.pattern = $4;
+		     node->v.xf.trans = compile_transform_expr($6, re_flags);
 	     }
 	   | UNSET IDENT
 	     {
@@ -626,37 +642,47 @@ environ_stmt: CLRENV
 	      {
 		     current_rule->clrenv = 1;
 	      }
-	    | SETENV IDENT string
+	    | SETENV IDENT '=' string
 	      {
 		     new_envar(current_rule,
 			       $2, strlen($2),
-			       $3, strlen($3),
+			       $4, strlen($4),
 			       envar_set);
 	      }
-	    | UNSETENV name_list
+	    | UNSETENV asgn_list
 	      {
-		      add_name_list($2.head, envar_unset);
+		      add_asgn_list($2.head, envar_unset);
 	      }
-	    | KEEPENV name_list
+	    | KEEPENV asgn_list
 	      {
-		      add_name_list($2.head, envar_keep);
+		      add_asgn_list($2.head, envar_keep);
 	      }
 	    ;
 
-name_list   : IDENT
+asgn_list   : asgn
 	      {
-		     struct name_entry *np = xmalloc(sizeof(*np));
-		     np->next = NULL;
-		     np->name = $1;
-		     $$.head = $$.tail = np;
+		      $$.head = $$.tail = $1;
 	      }
-	    | name_list IDENT
+	    | asgn_list asgn
 	      {
-		     struct name_entry *np = xmalloc(sizeof(*np));
-		     np->next = NULL;
-		     np->name = $2;
-		     LIST_APPEND(np, $1.head, $1.tail);
-		     $$ = $1;
+		      LIST_APPEND($2, $1.head, $1.tail);
+		      $$ = $1;
+	      }
+	    ;
+
+asgn        : IDENT
+	      {
+		     $$ = xmalloc(sizeof(*$$));
+		     $$->next = NULL;
+		     $$->name = $1;
+		     $$->value = NULL;
+	      }
+	    | IDENT '=' value
+	      {
+		     $$ = xmalloc(sizeof(*$$));
+		     $$->next = NULL;
+		     $$->name = $1;
+		     $$->value = $3;
 	      }
 	    ;
 
@@ -759,12 +785,12 @@ new_envar(struct rush_rule *rule,
 }
 
 static void
-add_name_list(struct name_entry *head, enum envar_type type)
+add_asgn_list(struct asgn *head, enum envar_type type)
 {
 	for (; head; head = head->next) {
 		new_envar(current_rule,
 			  head->name, strlen(head->name),
-			  NULL, 0,
+			  head->value, head->value ? strlen(head->value) : 0,
 			  type);
 		free(head->name);
 	}
diff --git a/src/cflex.l b/src/cflex.l
index a6f03c2..8d57f5b 100644
--- a/src/cflex.l
+++ b/src/cflex.l
@@ -171,7 +171,7 @@ rush[ \t]+2\.0[ \t]*$ {
   	        return tok(IDENT);
         }
 		}
-.   { straychar(yytext[0]); skiptoeol(); }
+.       return yytext[0];
 }
 
 <ARGS,INMATCH>{
@@ -180,7 +180,7 @@ rush[ \t]+2\.0[ \t]*$ {
 				return tok(NUMBER); }
 [A-Za-z_][A-Za-z0-9_-]*       { yylval.str = xstrdup(yytext);
 				return tok(IDENT); }
-[A-Za-z_+-][A-Za-z0-9_-]*     { yylval.str = xstrdup(yytext);
+[A-Za-z_/+-][A-Za-z0-9_/+-]*  { yylval.str = xstrdup(yytext);
 				return tok(STRING); }
 \$[A-Za-z_][A-Za-z_0-9-]*     { yylval.str = xstrdup(yytext);
 				return tok(STRING);  }
@@ -233,7 +233,17 @@ rush[ \t]+2\.0[ \t]*$ {
 					      strtoul(yytext + yyleng - 2,
 						      NULL, 16));
 			   pushstart(QSTR); }
-"~"|"("|")"|"["|"]"        return tok(yytext[0]);
+\"[^\\\"\n]*\\.          { struct cfloc loc;
+	                   loc.beg = loc.end = curloc.end;
+			   loc.beg.column -= 2;
+	                   cferror(&loc,
+				   _("unrecognized escape \\%c"),
+				   yytext[yyleng - 1]);
+			   stringbuf_init(&sb);
+			   stringbuf_add_array(&sb, yytext + 1, yyleng - 1);
+			   pushstart(QSTR); }
+"=~"                       return tok(XF);
+.                          return yytext[0];
 }
 
 <QSTR>{
@@ -261,8 +271,17 @@ rush[ \t]+2\.0[ \t]*$ {
 			   stringbuf_add_char(&sb,
 					      strtoul(yytext + yyleng - 2,
 						      NULL, 16)); }
+[^\\\"\n]*\\.            { struct cfloc loc;
+	                   loc.beg = loc.end = curloc.end;
+			   loc.beg.column -= 2;
+	                   cferror(&loc,
+				   _("unrecognized escape \\%c"),
+				   yytext + yyleng - 1);
+			   stringbuf_init(&sb);
+			   stringbuf_add_array(&sb, yytext, yyleng); }
 \n   {  advance_line(1);
 	yyerror("unescaped newline in quoted string"); }
+.    {  straychar(yytext[0]); }
 }
 
 <VAR>{
@@ -302,11 +321,10 @@ rush[ \t]+2\.0[ \t]*$ {
 						   strtoul(yytext + yyleng - 2,
 							   NULL, 16));
 				pushstart(QSTR); }
-[^}\"\$%]+                      { stringbuf_add_array(&sb, yytext, yyleng); }
+[^}\"\$%]+                    { stringbuf_add_array(&sb, yytext, yyleng); }
+.                             { straychar(yytext[0]);
+	                        stringbuf_add_char(&sb, yytext[0]); }
 }
-
-<INMATCH,ARGS,VAR,QSTR>.          { straychar(yytext[0]);
-				    return tok(BOGUS); }
 %%
 void
 straychar(int c)
diff --git a/src/map.c b/src/map.c
index dff68e2..d332bb5 100644
--- a/src/map.c
+++ b/src/map.c
@@ -16,6 +16,9 @@
 
 #include <rush.h>
 
+/* Set to 1 if expansion of undefined variables is allowed */
+int expand_undefined;
+
 static inline int
 d2n(int d)
 {
@@ -252,7 +255,7 @@ rush_expand_string(const char *string, struct rush_request *req)
 	struct wordsplit ws;
 	int wsflags = WRDSF_NOSPLIT
 		      | WRDSF_NOCMD
-		      | WRDSF_UNDEF
+		      | (expand_undefined ? 0: WRDSF_UNDEF)
 		      | WRDSF_GETVAR
 		      | WRDSF_CLOSURE;
 	char *result;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index c0877e8..c61ddd9 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -63,6 +63,15 @@ TESTSUITE_AT = \
   interactive.at\
   fallthrough.at\
   error.at\
+  clrenv.at\
+  unsetenv.at\
+  keepenv.at\
+  setenv.at\
+  backref.at\
+  setvar.at\
+  unsetvar.at\
+  undef.at\
+  regexp.at\
   legacy/argc.at\
   legacy/backref.at\
   legacy/chdir.at\
diff --git a/tests/backref.at b/tests/backref.at
new file mode 100644
index 0000000..a707d5d
--- /dev/null
+++ b/tests/backref.at
@@ -0,0 +1,43 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([Back-reference expansion])
+AT_KEYWORDS([backref])
+
+AT_RUSH_TEST([
+rush 2.0
+rule chdir
+  match \$command ~ "^cd \"(.+)\" && (runcom .*)$"
+  chdir %1
+  set command = %2
+  fall-through
+
+rule runcom
+  match \$0 == runcom
+  set [0] = "./bin/runcom"
+],
+[cmdline,home_dir],
+[cd "$PWD" && runcom test],
+[0],
+[{
+    "cmdline":"./bin/runcom test",
+    "home_dir":"$TESTDIR"
+}
+],
+[])
+
+AT_CLEANUP
+
diff --git a/tests/clrenv.at b/tests/clrenv.at
new file mode 100644
index 0000000..80c8acc
--- /dev/null
+++ b/tests/clrenv.at
@@ -0,0 +1,34 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2016-2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([clrenv])
+AT_KEYWORDS([clrenv])
+
+AT_RUSH_TEST([
+rush 2.0
+rule
+    clrenv
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[]]
+}
+],
+[])
+
+AT_CLEANUP
diff --git a/tests/fallthrough.at b/tests/fallthrough.at
index 787bcc1..e7f1aab 100644
--- a/tests/fallthrough.at
+++ b/tests/fallthrough.at
@@ -20,11 +20,11 @@ AT_KEYWORDS([fallthrough fall-through])
 AT_RUSH_TEST([
 rush 2.0
 rule
-    set [0] newcommand
+    set [0] = newcommand
     fall-through
     
 rule
-    set [1] list
+    set [1] = list
 ],
 [cmdline,argv],
 [command],
@@ -46,7 +46,7 @@ rule
     fall-through
     
 rule
-    set [0] newcommand
+    set [0] = newcommand
     interactive true
 ],
 [cmdline,interactive,home_dir],
diff --git a/tests/keepenv.at b/tests/keepenv.at
new file mode 100644
index 0000000..a3e1c4a
--- /dev/null
+++ b/tests/keepenv.at
@@ -0,0 +1,40 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2016-2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([keepenv])
+AT_KEYWORDS([keepenv])
+
+m4_pushdef([RUSH_ENVIRON],[-i HOME=$PWD USER=$MY_USER LOGIN=NO_$MY_USER PATH=$PATH])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    clrenv
+    keepenv HOME USER
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "HOME=$TESTDIR",
+        "USER=$MY_USER"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+AT_CLEANUP
diff --git a/tests/regexp.at b/tests/regexp.at
new file mode 100644
index 0000000..1708471
--- /dev/null
+++ b/tests/regexp.at
@@ -0,0 +1,88 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([regexp options])
+AT_KEYWORDS([match regexp])
+
+AT_RUSH_TEST([
+rush 2.0
+rule
+  match \$command ~ "fo+\$"
+],
+[cmdline,argv],
+[ls foo],
+[0],
+[{
+    "cmdline":"ls foo",
+    "argv":[[
+        "ls",
+        "foo"
+    ]]
+}
+],
+[])
+
+AT_RUSH_TEST([
+rush 2.0
+global
+  regexp basic
+rule
+  match \$command ~ "fo+\$"
+],
+[cmdline,argv],
+
+[ls foo],
+[1],
+[],
+[rush: Error: no matching rule for "ls foo", user $MY_USER
+],
+
+[ls fo+],
+[0],
+[{
+    "cmdline":"ls fo+",
+    "argv":[[
+        "ls",
+        "fo+"
+    ]]
+}
+],
+[])
+
+AT_RUSH_TEST([
+rush 2.0
+global
+  regexp basic ignore-case
+rule
+  match \$command ~ "fo+\$"
+],
+[cmdline,argv],
+
+[ls Fo+],
+[0],
+[{
+    "cmdline":"ls Fo+",
+    "argv":[[
+        "ls",
+        "Fo+"
+    ]]
+}
+],
+[])
+
+
+AT_CLEANUP
+
diff --git a/tests/set.at b/tests/set.at
index 668945d..599f73d 100644
--- a/tests/set.at
+++ b/tests/set.at
@@ -20,7 +20,7 @@ AT_KEYWORDS([set])
 AT_RUSH_TEST([
 rush 2.0
 rule
-  set command "ls /"
+  set command = "ls /"
 ],
 [cmdline,argv,prog],
 [echo],
@@ -39,7 +39,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-  set [0] "/usr/bin/\$0" 
+  set [0] = "/usr/bin/\$0" 
 ],
 [cmdline,argv,prog],
 [ls /],
@@ -58,7 +58,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-  set [1] "/chroot\${1}" 
+  set [1] = "/chroot\${1}" 
 ],
 [cmdline,argv,prog],
 [ls /],
@@ -77,7 +77,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-  set program "/usr/bin/ls"
+  set program = "/usr/bin/ls"
 ],
 [cmdline,argv,prog],
 [ls /],
@@ -96,7 +96,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-  set [-1] "/tmp"
+  set [-1] = "/tmp"
 ],
 [cmdline,argv,prog],
 [ls /],
diff --git a/tests/setenv.at b/tests/setenv.at
new file mode 100644
index 0000000..66ad12b
--- /dev/null
+++ b/tests/setenv.at
@@ -0,0 +1,130 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2016-2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([setenv])
+AT_KEYWORDS([setenv])
+
+m4_pushdef([RUSH_ENVIRON],[-i HOME=$PWD USER=$MY_USER])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    setenv NEWVAR=foo
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "HOME=$TESTDIR",
+        "NEWVAR=foo",
+        "USER=$MY_USER"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+m4_pushdef([RUSH_ENVIRON],[-i])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    setenv MYPATH="\${MYPATH:-}\${MYPATH+:}/usr/local/bin"
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "MYPATH=/usr/local/bin"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+m4_pushdef([RUSH_ENVIRON],[-i MYPATH=/bin:/usr/bin])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    setenv MYPATH="\${MYPATH:-}\${MYPATH+:}/usr/local/bin"
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "MYPATH=/bin:/usr/bin:/usr/local/bin"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+m4_pushdef([RUSH_ENVIRON],[-i])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    setenv MYPATH="/usr/local/bin\${MYPATH+:}\${MYPATH:-}"
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "MYPATH=/usr/local/bin"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+m4_pushdef([RUSH_ENVIRON],[-i MYPATH=/bin:/usr/bin])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    setenv MYPATH="/usr/local/bin\${MYPATH+:}\$MYPATH"
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "MYPATH=/usr/local/bin:/bin:/usr/bin"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+m4_pushdef([RUSH_ENVIRON],[-i MYPATH=/bin:/usr/bin])
+AT_RUSH_TEST([
+rush 2.0
+rule
+    setenv MYPATH="/usr/local/bin:\$MYPATH"
+],
+[environ],
+[command],
+[0],
+[{
+    "environ":[[
+        "MYPATH=/usr/local/bin:/bin:/usr/bin"
+    ]]
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+AT_CLEANUP
diff --git a/tests/setvar.at b/tests/setvar.at
new file mode 100644
index 0000000..3017f63
--- /dev/null
+++ b/tests/setvar.at
@@ -0,0 +1,43 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([setvar])
+AT_KEYWORDS([setvar])
+AT_RUSH_TEST([
+rush 2.0
+rule first
+  set home = "$PWD"
+  set count = 1
+  set FOO =  bar
+  fall-through
+
+rule last
+  set command = "\$FOO \$count"
+],
+[cmdline,vars],
+[ls],
+[0],
+[{
+    "cmdline":"bar 1",
+    "vars":{
+        "FOO":"bar",
+        "count":"1",
+        "home":"$TESTDIR"
+    }
+}
+],
+[])
+AT_CLEANUP
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 61b348c..e10d4b8 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -56,12 +56,16 @@ AT_INIT
 AT_TESTED([rush])
 
 m4_include([null.at])
+m4_include([setvar.at])
+m4_include([unsetvar.at])
+m4_include([undef.at])
 
 AT_BANNER([Simple Conditions])
 m4_include([argc.at])
 m4_include([command.at])
 m4_include([matcharg.at])
 m4_include([matchprog.at])
+m4_include([regexp.at])
 m4_include([uid.at])
 m4_include([user.at])
 m4_include([in.at])
@@ -85,12 +89,21 @@ m4_include([newgrp.at])
 m4_include([chdir.at])
 m4_include([interactive.at])
 
-AT_BANNER([Flow control])
+AT_BANNER([Environment])
+m4_include([clrenv.at])
+m4_include([unsetenv.at])
+m4_include([keepenv.at])
+m4_include([setenv.at])
 
-AT_BANNER([Legacy configuration])
+AT_BANNER([Features])
+m4_include([backref.at])
+
+AT_BANNER([Flow control])
 m4_include([fallthrough.at])
 m4_include([error.at])
 
+AT_BANNER([Legacy configuration])
+
 dnl AT_BANNER([Conditionals])
 m4_include([legacy/argc.at])
 m4_include([legacy/command.at])
diff --git a/tests/transform.at b/tests/transform.at
index bbd0fb1..ee56448 100644
--- a/tests/transform.at
+++ b/tests/transform.at
@@ -20,7 +20,7 @@ AT_KEYWORDS([transform])
 AT_RUSH_TEST([
 rush 2.0
 rule
-    set command ~ "s/^[^[:space:]]+/& -t/"
+    set command =~ "s/^[^[:space:]]+/& -t/"
 ],
 [cmdline,argv,prog],
 [svnserve],
@@ -39,7 +39,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-    set command "\${command} end" ~ "s/[[:space:]]+-[^[:space:]]+//g"
+    set command = "\${command} end" ~ "s/[[:space:]]+-[^[:space:]]+//g"
 ],
 [cmdline,argv,prog],
 [echo -c -t foo -n bar],
@@ -60,7 +60,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-    set [0] ~ "s|^[^/]|/usr/bin/&|"
+    set [0] =~ "s|^[^/]|/usr/bin/&|"
 ],
 [cmdline,argv,prog],
 [echo foo],
@@ -92,7 +92,7 @@ rule
 AT_RUSH_TEST([
 rush 2.0
 rule
-    set [0] \$program ~ "s,.*/,-,"
+    set [0] = \$program ~ "s,.*/,-,"
 ],
 [cmdline,argv,prog],
 [/bin/sh],
diff --git a/tests/undef.at b/tests/undef.at
new file mode 100644
index 0000000..015dd52
--- /dev/null
+++ b/tests/undef.at
@@ -0,0 +1,65 @@
+# This file is part of GNU Rush. 
+# Copyright (C) 2019 Sergey Poznyakoff
+#
+# GNU Rush is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Rush is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNU Rush.  If not, see <http://www.gnu.org/licenses/>.
+
+AT_SETUP([expanding undefined variables])
+AT_KEYWORDS([undef])
+
+m4_pushdef([RUSH_ENVIRON],[-i])
+AT_RUSH_TEST([
+rush 2.0
+rule first
+  set command = \$COMMAND
+],
+[cmdline],
+[ls],
+[1],
+[],
+[rush: Error: undefined variable
+])
+
+AT_RUSH_TEST([
+rush 2.0
+rule first
+  set command = \${COMMAND:-\$command}
+],
+[cmdline],
+[ls],
+[0],
+[{
+    "cmdline":"ls"
+}
+],
+[])
+
+AT_RUSH_TEST([
+rush 2.0
+global
+  expand-undefined true
+
+rule first
+  set command = \$COMMAND
+],
+[cmdline],
+[ls],
+[0],
+[{
+    "cmdline":""
+}
+],
+[])
+m4_popdef([RUSH_ENVIRON])
+
+AT_CLEANUP