begin adding tests for regex

test/regex-tests.sml

@@ -0,0 +1,43 @@
+structure RegexTests =
+struct
+  open Railroad
+  open Railroad.Test
+
+  structure CiDfa = CaseInsensitiveDfa
+  structure CsDfa = CaseSensitiveDfa
+
+  val caseInsensitiveTests = describe "case insensitive regex"
+    [ test "recognises word 'hello' in string 'Hello world'" (fn _ =>
+        let
+          (* arrange *)
+          val regexString = "hello"
+          val dfa = CiDfa.fromString regexString
+          val inputString = "Hello world"
+
+          (* act *)
+          val matches = CiDfa.matchString (dfa, inputString)
+
+          (* assert *)
+          val expectedMatches = [(0, 4)]
+        in
+          Expect.isTrue (matches = expectedMatches)
+        end)
+    , test "recognises word 'world' in string 'HELLO WORLD'" (fn _ =>
+        let
+          (* arrange *)
+          val regexString = "world"
+          val dfa = CiDfa.fromString regexString
+          val inputString = "HELLO WORLD"
+
+          (* act *)
+          val matches = CiDfa.matchString (dfa, inputString)
+
+          (* assert *)
+          val expectedMatches = [(6, 10)]
+        in
+          Expect.isTrue (matches = expectedMatches)
+        end)
+    ]
+
+  val tests = [caseInsensitiveTests]
+end

test/test.sml

@@ -6,7 +6,12 @@ struct
   fun main () =
     let
       val tests =
-        List.concat [NormalMove.tests, NormalDelete.tests, Regression.tests]
+        List.concat
+          [ NormalMove.tests
+          , NormalDelete.tests
+          , Regression.tests
+          , RegexTests.tests
+          ]
       val tests = concat tests
     in
       runWithConfig [Configuration.PrintPassed false] tests