Add Range#intersect?. Refs #5299

2 files changed, 32 insertions, 2 deletions

diff --git a/lib/range_ext.rb b/lib/range_ext.rb
index a6a3bfc5d..e7e0e903f 100644
--- a/lib/range_ext.rb
+++ b/lib/range_ext.rb
@@ -1,11 +1,15 @@
 class Range
 
   def intersection(other)
-    return nil if (self.max < other.min or other.max < self.min)
+    return nil unless intersect?(other)
     [self.min, other.min].max..[self.max, other.max].min
   end
   alias_method :&, :intersection
 
+  def intersect?(other)
+    self.max > other.min and other.max > self.min
+  end
+
   def remove(other)
     return self if (self.max < other.min or other.max < self.min)
 
diff --git a/spec/lib/range_ext_spec.rb b/spec/lib/range_ext_spec.rb
index cae637e47..eee488c91 100644
--- a/spec/lib/range_ext_spec.rb
+++ b/spec/lib/range_ext_spec.rb
@@ -1,6 +1,6 @@
 require 'range_ext'
 RSpec.describe Range do
-  context "intersection" do
+  describe "#intersection" do
     it "is nil (sic) for two distinct ranges" do
       expect( (1..2).intersection(3..4) ).to be_nil
     end
@@ -16,6 +16,32 @@ RSpec.describe Range do
     end
   end
 
+  describe "intersect?" do
+    it 'is true when the given range includes begin' do
+      expect( (2..4).intersect? (1..3) ).to be_truthy
+    end
+
+    it 'is true when the given range includes end' do
+      expect( (2..4).intersect? (3..5) ).to be_truthy
+    end
+
+    it 'is true when the given range includes both begin and end' do
+      expect( (2..4).intersect? (1..5) ).to be_truthy
+    end
+
+    it 'is true when the given range is the same' do
+      expect( (2..4).intersect? (2..4) ).to be_truthy
+    end
+
+    it 'is false when the given range is after' do
+      expect( (2..4).intersect? (5..7) ).to be_falsey
+    end
+
+    it 'is false when the given range is before' do
+      expect( (2..4).intersect? (0..2) ).to be_falsey
+    end
+  end
+
   context "remove" do
     it "is unchanged when the given range has no intersection" do
       expect( (1..2).remove(3..4) ).to eq 1..2