From 1a9792afb92e227adcb564a051b678faa9fe2036 Mon Sep 17 00:00:00 2001
From: Matthew Hall <hallmatthew314@gmail.com>
Date: Thu, 9 Mar 2023 16:52:30 +1300
Subject: Implement Exactly + extra test for Sequence

---
 spec/parcom_spec.cr | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

(limited to 'spec')

diff --git a/spec/parcom_spec.cr b/spec/parcom_spec.cr
index 9051cb7..713445f 100644
--- a/spec/parcom_spec.cr
+++ b/spec/parcom_spec.cr
@@ -401,6 +401,15 @@ describe Sequence do
         expect_raises(ParserException) { p.parse(tokens) }
       end
     end
+
+    it "succeeds and returns empty array if parser iterable is empty" do
+      tokens = TokenStream.from_string("abcd")
+      empty_p = Sequence.new([] of Parser(Char, Char))
+      result = empty_p.parse(tokens)
+
+      result.value.empty?.should be_true
+      result.tokens.should eq(tokens)
+    end
   end
 end
 
@@ -480,7 +489,46 @@ describe Some do
   end
 end
 
-pending Exactly do
+describe Exactly do
+  letter_a = Token.new('a')
+  tokens = TokenStream.from_string("aaabcd")
+
+  describe "#parse" do
+    it "tries to parse exactly n of the wrapper parser" do
+      p = Exactly.new(3, letter_a)
+      result = p.parse(tokens)
+
+      result.value.should eq("aaa".chars)
+      result.tokens.should eq(tokens[3..])
+    end
+
+    it "always succeeds with an empty array if n < 1" do
+      p = Exactly.new(0, letter_a)
+      result = p.parse(tokens)
+
+      result.value.empty?.should be_true
+      result.tokens.should eq(tokens)
+
+      p = Exactly.new(-42, letter_a)
+      result = p.parse(tokens)
+
+      result.value.empty?.should be_true
+      result.tokens.should eq(tokens)
+    end
+
+    it "does not take extra matching tokens" do
+      p = Exactly.new(2, letter_a)
+      result = p.parse(tokens)
+
+      result.value.should eq("aa".chars)
+      result.tokens.should eq(tokens[2..])
+    end
+
+    it "fails if there are not enough matching tokens" do
+      p = Exactly.new(60, letter_a)
+      expect_raises(ParserException) { p.parse(tokens) }
+    end
+  end
 end
 
 pending AtLeast do
-- 
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