Add tests.toml file for grains exercise (#393)

Author: ErikSchierboom

exercises/grains/.meta/tests.toml

@@ -0,0 +1,34 @@
+[canonical-tests]
+
+# 1
+"9fbde8de-36b2-49de-baf2-cd42d6f28405" = true
+
+# 2
+"ee1f30c2-01d8-4298-b25d-c677331b5e6d" = true
+
+# 3
+"10f45584-2fc3-4875-8ec6-666065d1163b" = true
+
+# 4
+"a7cbe01b-36f4-4601-b053-c5f6ae055170" = true
+
+# 16
+"c50acc89-8535-44e4-918f-b848ad2817d4" = true
+
+# 32
+"acd81b46-c2ad-4951-b848-80d15ed5a04f" = true
+
+# 64
+"c73b470a-5efb-4d53-9ac6-c5f6487f227b" = true
+
+# square 0 raises an exception
+"1d47d832-3e85-4974-9466-5bd35af484e3" = true
+
+# negative square raises an exception
+"61974483-eeb2-465e-be54-ca5dde366453" = true
+
+# square greater than 64 raises an exception
+"a95e4374-f32c-45a7-a10d-ffec475c012f" = true
+
+# returns the total number of grains on the board
+"6eb07385-3659-4b45-a6be-9dc474222750" = true