Add test

It takes a long time to run, but it is basically all
the testing we need of the API, if this works it's
unlikely to be broken. It requires  a change in the build
system, so don't enable it for now.

tests/idris2/api001/Hello.idr

@@ -0,0 +1,2 @@
+main : IO ()
+main = putStrLn "Hello"

tests/idris2/api001/LazyCodegen.idr

@@ -0,0 +1,19 @@
+module Main
+
+import Core.Context
+import Compiler.Common
+import Idris.Driver
+
+compile : Ref Ctxt Defs -> (execDir : String) ->
+          ClosedTerm -> (outfile : String) -> Core (Maybe String)
+compile defs dir term file = do coreLift $ putStrLn "I'd rather not."
+                                pure $ Nothing
+
+execute : Ref Ctxt Defs -> (execDir : String) -> ClosedTerm -> Core ()
+execute defs dir term = do coreLift $ putStrLn "Maybe in an hour."
+
+lazyCodegen : Codegen
+lazyCodegen = MkCG compile execute
+
+main : IO ()
+main = mainWithCodegens [("lazy", lazyCodegen)]

tests/idris2/api001/expected

@@ -0,0 +1 @@
+I'd rather not.

tests/idris2/api001/run

@@ -0,0 +1,3 @@
+$1 --no-banner -p idris2 -p contrib -p network LazyCodegen.idr -o lazy-idris2 > /dev/null
+./build/exec/lazy-idris2 --no-banner --cg lazy Hello.idr -o hello
+rm -rf build