Allow verifying prerequisites!

test/test-prereqs

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+testShouldBailIfRequirementsNotMet() {
+  echo '
+  #!/usr/bin/env bash
+
+  _verify-prerequisites() { false; }
+  ⚡️hello() { echo "Hello, World!" ; }
+  ' > go
+
+  echo "source $REPO_ROOT/⚡️" >> go
+  chmod +x go
+
+  try ./go
+  assertNotContains "$STDOUT" "hello"
+  assertEquals 1 "$EXIT_CODE"
+}
+
+testShouldNotBailWhenPrereqsAreAllGood() {
+  echo '
+  #!/usr/bin/env bash
+
+  _verify-prerequisites() { true; }
+  ⚡️hello() { echo "Hello, World!" ; }
+  ' > go
+
+  echo "source $REPO_ROOT/⚡️" >> go
+  chmod +x go
+
+  try ./go
+  assertContains "$STDOUT" "hello"
+  assertEquals 0 "$EXIT_CODE"
+}
+
+source $(dirname $0)/runner