Added unit test for missing symbol in table

Builds a goto program with one assert and checks that: 1) with the right symbol
in the table the validation succeeds, 2) without the symbol the validation
fails.

Author: Petr Bauch

unit/Makefile

@@ -15,6 +15,7 @@ SRC += analyses/ai/ai.cpp \
        analyses/does_remove_const/does_type_preserve_const_correctness.cpp \
        analyses/does_remove_const/is_type_at_least_as_const_as.cpp \
        goto-programs/goto_trace_output.cpp \
+       goto-programs/goto_program_table_consistency.cpp \
        interpreter/interpreter.cpp \
        json/json_parser.cpp \
        path_strategies.cpp \

unit/goto-programs/goto_program_table_consistency.cpp

@@ -0,0 +1,63 @@
+/*******************************************************************\
+
+ Module: Unit tests for goto_program::validate
+
+ Author: Diffblue Ltd.
+
+\*******************************************************************/
+
+#include <goto-programs/goto_function.h>
+#include <testing-utils/catch.hpp>
+#include <util/arith_tools.h>
+
+SCENARIO(
+  "Validation of consistent program/table pair",
+  "[core][goto-programs][validate]")
+{
+  GIVEN("A program with one assertion")
+  {
+    symbol_tablet symbol_table;
+    const typet type = signedbv_typet(32);
+    symbolt symbol;
+    irep_idt symbol_name = "a";
+    symbol.name = symbol_name;
+    symbol_exprt varx(symbol_name, type);
+
+    exprt val10 = from_integer(10, type);
+    binary_relation_exprt x_le_10(varx, ID_le, val10);
+
+    goto_functiont goto_function;
+    auto &instructions = goto_function.body.instructions;
+    instructions.emplace_back(goto_program_instruction_typet::ASSERT);
+    instructions.back().make_assertion(x_le_10);
+
+    WHEN("Symbol table has the right symbol")
+    {
+      symbol_table.insert(symbol);
+
+      THEN("The consistency check succeeds")
+      {
+        goto_function.validate(symbol_table, validation_modet::INVARIANT);
+
+        REQUIRE(true);
+      }
+    }
+
+    WHEN("Symbol table does not have the symbol")
+    {
+      THEN("The consistency check fails")
+      {
+        bool caught = false;
+        try
+        {
+          goto_function.validate(symbol_table, validation_modet::EXCEPTION);
+        }
+        catch(incorrect_goto_program_exceptiont &e)
+        {
+          caught = true;
+        }
+        REQUIRE(caught);
+      }
+    }
+  }
+}