Add unit tests for expr_iterator

Author: smowton

unit/Makefile

@@ -50,6 +50,7 @@ SRC += analyses/ai/ai.cpp \
        util/cmdline.cpp \
        util/expr_cast/expr_cast.cpp \
        util/expr.cpp \
+       util/expr_iterator.cpp \
        util/file_util.cpp \
        util/format_number_range.cpp \
        util/get_base_name.cpp \

unit/util/expr_iterator.cpp

@@ -0,0 +1,103 @@
+/*******************************************************************\
+
+Module: Unit tests for expr_iterator
+
+Author: Diffblue Ltd
+
+\*******************************************************************/
+
+/// \file
+/// expr_iterator unit tests
+
+#include <testing-utils/use_catch.h>
+
+#include <util/expr_iterator.h>
+#include <util/std_expr.h>
+
+SCENARIO("expr_iterator", "[core][utils][expr_iterator]")
+{
+  GIVEN("An expression of depth 3")
+  {
+    symbol_exprt symbol("whatever", bool_typet());
+    notequal_exprt middle1(symbol, symbol);
+    equal_exprt middle2(symbol, symbol);
+    implies_exprt top(middle1, middle2);
+
+    WHEN("Visiting the expressions with a depth iterator")
+    {
+      std::vector<irep_idt> ids;
+      for(auto it = top.depth_begin(), itend = top.depth_end(); it != itend;
+          ++it)
+      {
+        ids.push_back(it->id());
+      }
+
+      THEN("We expect to see parents before children")
+      {
+        REQUIRE(
+          ids == std::vector<irep_idt>{ID_implies,
+                                       ID_notequal,
+                                       ID_symbol,
+                                       ID_symbol,
+                                       ID_equal,
+                                       ID_symbol,
+                                       ID_symbol});
+      }
+    }
+
+    WHEN("Replacing one of the middle nodes mid-walk")
+    {
+      std::vector<irep_idt> ids;
+      for(auto it = top.depth_begin(), itend = top.depth_end(); it != itend;
+          ++it)
+      {
+        if(it->id() == ID_notequal)
+          it.mutate() = not_exprt(equal_exprt(symbol, symbol));
+
+        ids.push_back(it->id());
+      }
+
+      THEN("We expect to see the newly added child nodes")
+      {
+        REQUIRE(
+          ids == std::vector<irep_idt>{ID_implies,
+                                       ID_not,
+                                       ID_equal,
+                                       ID_symbol,
+                                       ID_symbol,
+                                       ID_equal,
+                                       ID_symbol,
+                                       ID_symbol});
+      }
+    }
+
+    WHEN(
+      "Replacing one of the middle nodes mid-walk and skipping the new "
+      "children")
+    {
+      std::vector<irep_idt> ids;
+      for(auto it = top.depth_begin(), itend = top.depth_end(); it != itend;
+          /* no ++it */)
+      {
+        bool replace_here = it->id() == ID_notequal;
+
+        if(replace_here)
+          it.mutate() = not_exprt(equal_exprt(symbol, symbol));
+
+        ids.push_back(it->id());
+
+        if(replace_here)
+          it.next_sibling_or_parent();
+        else
+          ++it;
+      }
+
+      THEN("We expect to skip the newly added child nodes")
+      {
+        REQUIRE(
+          ids == std::vector<irep_idt>{
+                   ID_implies, ID_not, ID_equal, ID_symbol, ID_symbol});
+      }
+    }
+  }
+}