EssentialTypes: Add basic test case for library.

Author: lcartey

c/misra/test/c/misra/EssentialTypes.expected

@@ -0,0 +1,5 @@
+import codingstandards.c.misra.EssentialTypes
+
+from Expr e
+select e, getEssentialType(e) as et, getEssentialTypeBeforeConversions(e),
+  getEssentialTypeCategory(et)

c/misra/test/c/misra/EssentialTypes.ql

@@ -0,0 +1,17 @@
+#include <stdbool.h>
+
+void testConditional() {
+  unsigned int u = 1;
+  unsigned short us = 1;
+  signed int s = 1;
+  signed short ss = 1;
+  _Bool b = true;
+
+  b ? u : u;  // unsigned int
+  b ? s : s;  // signed int
+  b ? s : ss; // signed int
+  b ? ss : s; // signed int
+  b ? us : u; // unsigned int
+
+  b ? s : u; // unsigned int
+}