test(tests/lean/run/ematch1): add ematching example

tests/lean/run/ematch1.lean

@@ -0,0 +1,33 @@
+constant f : nat → nat
+constant g : nat → nat
+axiom Ax : ∀ x, (: f (g x) :) = x
+
+open tactic
+
+meta def add_insts : list (expr × expr) → tactic unit
+| []              := skip
+| ((inst, pr)::r) := do
+  assertv `_einst inst pr,
+  add_insts r
+
+meta def ematch_test (h : name) (e : expr) : tactic unit :=
+do cc  ← cc_state.mk_using_hs,
+   ems ← return $ ematch_state.mk 10000,
+   hlemma ← hinst_lemma.mk_from_decl h,
+   (r, cc, ems) ← ematch cc ems hlemma e,
+   add_insts r
+
+example (a b c : nat) : f a = b → a = g c → f a ≠ c → false :=
+by do
+  intros,
+  e ← to_expr `(f a),
+  ematch_test `Ax e,
+  trace_state,
+  cc
+
+example (a b c : nat) : f a = b → a = g c → f a = c :=
+by do
+  intros,
+  e ← to_expr `(f a),
+  ematch_test `Ax e,
+  cc