add unit tests for some sigstring functions

Author: calebstein1

spec/sigstring_spec.rb

@@ -0,0 +1,44 @@
+require 'fiddle'
+
+RSpec.describe "sigstring functions" do
+  describe "sigstrlen" do
+    it "returns the length of a string" do
+      str = "Hello, world!"
+      len = SigString.sigstrlen(str)
+      expect(len).to eq(str.length)
+    end
+
+    it "returns the length of an empty string" do
+      str = ""
+      len = SigString.sigstrlen(str)
+      expect(len).to eq(str.length)
+    end
+  end
+
+  describe "sigstrcpy" do
+    it "copies a string from one location to another" do
+      str = "Hello, world!"
+      buffer = Fiddle::Pointer.malloc(str.length + 1, Fiddle::RUBY_FREE)
+      SigString.sigstrcpy(buffer, str)
+      expect(buffer.to_s).to eq(str)
+    end
+  end
+
+  describe "sigstrncpy" do
+    it "copies a portion of a string from one location to another" do
+      str = "Hello, world!"
+      n_chars = 5
+      buffer = Fiddle::Pointer.malloc(n_chars + 1, Fiddle::RUBY_FREE)
+      SigString.sigstrncpy(buffer, str, n_chars)
+      expect(buffer.to_s).to eq("Hello")
+    end
+
+    it "copies a string to the end of a buffer" do
+      str = "Hello, world!"
+      n_chars = 24
+      buffer = Fiddle::Pointer.malloc(n_chars, Fiddle::RUBY_FREE)
+      SigString.sigstrncpy(buffer, str, n_chars)
+      expect(buffer.to_s).to eq(str)
+    end
+  end
+end