Add simple tests for ppxlib-pp-ast

Signed-off-by: Nathan Rebours <[email protected]>

test/ppxlib-pp-ast/basic/dune

@@ -0,0 +1,3 @@
+(cram
+ (deps
+  (package ppxlib)))

test/ppxlib-pp-ast/basic/run.t

@@ -0,0 +1,77 @@
+ppxlib-pp-ast is a simple utility to pretty-print the AST corresponding
+to a given piece of source code or a marshalled AST.
+
+It can be used on regular .ml files:
+
+  $ cat > test.ml << EOF
+  > let x = x + 2
+  > EOF
+  $ ppxlib-pp-ast test.ml
+  [ Pstr_value
+      ( Nonrecursive
+      , [ { pvb_pat = Ppat_var "x"
+          ; pvb_expr =
+              Pexp_apply
+                ( Pexp_ident (Lident "+")
+                , [ ( Nolabel, Pexp_ident (Lident "x"))
+                  ; ( Nolabel, Pexp_constant (Pconst_integer ( "2", None)))
+                  ]
+                )
+          ; pvb_attributes = __attrs
+          ; pvb_loc = __loc
+          }
+        ]
+      )
+  ]
+
+on .mli files:
+
+  $ cat > test.mli << EOF
+  > val x : int
+  > EOF
+  $ ppxlib-pp-ast test.mli
+  [ Psig_value
+      { pval_name = "x"
+      ; pval_type = Ptyp_constr ( Lident "int", [])
+      ; pval_prim = []
+      ; pval_attributes = __attrs
+      ; pval_loc = __loc
+      }
+  ]
+
+But it can also be used to pretty a single expression:
+
+  $ ppxlib-pp-ast --exp - << EOF
+  > x + 2
+  > EOF
+  Pexp_apply
+    ( Pexp_ident (Lident "+")
+    , [ ( Nolabel, Pexp_ident (Lident "x"))
+      ; ( Nolabel, Pexp_constant (Pconst_integer ( "2", None)))
+      ]
+    )
+
+on a single pattern:
+
+  $ ppxlib-pp-ast --pat - << EOF
+  > (x, _::tl)
+  > EOF
+  Ppat_tuple
+    [ Ppat_var "x"
+    ; Ppat_construct
+        ( Lident "::", Some ( [], Ppat_tuple [ Ppat_any; Ppat_var "tl"]))
+    ]
+
+or on a single core_type:
+
+  $ ppxlib-pp-ast --typ - << EOF
+  > (int * string) result
+  > EOF
+  Ptyp_constr
+    ( Lident "result"
+    , [ Ptyp_tuple
+          [ Ptyp_constr ( Lident "int", [])
+          ; Ptyp_constr ( Lident "string", [])
+          ]
+      ]
+    )