Implement assert directive

The grammar is as follows:

assert <expression> [<description>]
assert! <expression> [<description>]

The expression must evaluate to 'true' or 'false', just like in if-else.

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/directive/common.test b/tests/directive/common.test
new file mode 100644
index 0000000..351c133
--- /dev/null
+++ b/tests/directive/common.test
@@ -0,0 +1,11 @@
+# file      : tests/directive/assert.test
+# copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+# license   : MIT; see accompanying LICENSE file
+
++mkdir build
++cat <<EOI >>>build/bootstrap.build
+project = test
+amalgamation =
+EOI
+
+test.options += -q --buildfile - noop