From e15429efdae301d623cae0e4ad3ba72739341cae Mon Sep 17 00:00:00 2001
From: Andrej Makarov <andrej.makarov@skrt.biz>
Date: Wed, 1 Feb 2017 08:24:22 +0000
Subject: [PATCH] Add exercise: secret-handshake

---
 config.json                                   | 13 ++++-
 exercises/secret-handshake/example.jl         | 12 +++++
 exercises/secret-handshake/runtests.jl        | 51 +++++++++++++++++++
 .../secret-handshake/secret-handshake.jl      |  3 ++
 4 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 exercises/secret-handshake/example.jl
 create mode 100644 exercises/secret-handshake/runtests.jl
 create mode 100644 exercises/secret-handshake/secret-handshake.jl

diff --git a/config.json b/config.json
index f6952debd4222..ffde4261f8e46 100644
--- a/config.json
+++ b/config.json
@@ -53,8 +53,8 @@
       "difficulty": 1,
       "topics": [
         "control-flow (conditionals)",
-				"integers",
-				"mathematics"
+        "integers",
+		"mathematics"
       ]
     },
     {
@@ -96,6 +96,15 @@
         "integers",
         "mathematics"
       ]
+    },
+    {
+      "slug": "secret-handshake",
+      "difficulty": 2,
+      "topics": [
+        "arrays",
+        "filtering",
+        "mathematics"
+      ]
     }
   ],
   "deprecated": [
diff --git a/exercises/secret-handshake/example.jl b/exercises/secret-handshake/example.jl
new file mode 100644
index 0000000000000..b5ed01e19525b
--- /dev/null
+++ b/exercises/secret-handshake/example.jl
@@ -0,0 +1,12 @@
+function secret_handshake(code::Integer)
+    # NOTE: Handle wrong codes
+    # code < 0 && error("Invalid secret handshake code")
+    # NOTE: Handle common actions
+    masks = [(1, "wink"), (2, "double blink"),
+             (4, "close your eyes"), (8, "jump")]
+    actions = map(x->code&x[1]==x[1]&&x[2], masks)
+    filter!(x->x!=false, actions)
+    # NOTE: Handle reversing bitmask
+    code&16==16 && reverse!(actions)
+    actions
+end
diff --git a/exercises/secret-handshake/runtests.jl b/exercises/secret-handshake/runtests.jl
new file mode 100644
index 0000000000000..7a8579ab001f7
--- /dev/null
+++ b/exercises/secret-handshake/runtests.jl
@@ -0,0 +1,51 @@
+using Base.Test
+
+include("secret-handshake.jl")
+
+@testset "wink for 1" begin
+    @test secret_handshake(1) == ["wink"]
+end
+
+@testset "double blink for 10" begin
+    @test secret_handshake(2) == ["double blink"]
+end
+
+@testset "close your eyes for 100" begin
+    @test secret_handshake(4) == ["close your eyes"]
+end
+
+@testset "jump for 1000" begin
+    @test secret_handshake(8) == ["jump"]
+end
+
+@testset "combine two actions" begin
+    @test secret_handshake(3) == ["wink", "double blink"]
+end
+
+@testset "reverse two actions" begin
+    @test secret_handshake(19) == ["double blink", "wink"]
+end
+
+@testset "reversing one action gives the same action" begin
+    @test secret_handshake(24) == ["jump"]
+end
+
+@testset "reversing no actions still gives no actions" begin
+    @test secret_handshake(16) == []
+end
+
+@testset "all possible actions" begin
+    @test secret_handshake(15) == ["wink", "double blink", "close your eyes", "jump"]
+end
+
+@testset "reverse all possible actions" begin
+    @test secret_handshake(31) == ["jump", "close your eyes", "double blink", "wink"]
+end
+
+@testset "do nothing for zero" begin
+    @test secret_handshake(0) == []
+end
+
+@testset "do nothing if lower 5 bits not set" begin
+    @test secret_handshake(32) == []
+end
diff --git a/exercises/secret-handshake/secret-handshake.jl b/exercises/secret-handshake/secret-handshake.jl
new file mode 100644
index 0000000000000..556c5c7ac8033
--- /dev/null
+++ b/exercises/secret-handshake/secret-handshake.jl
@@ -0,0 +1,3 @@
+function secret_handshake(code::Integer)
+
+end