Merge pull request #932 from mbj/add/range-overlap

Addrange Mutant::Range.overlap?

Author: mbj

lib/mutant.rb

@@ -182,6 +182,7 @@ module Mutant
 require 'mutant/repository'
 require 'mutant/variable'
 require 'mutant/zombifier'
+require 'mutant/range'
 
 module Mutant
   WORLD = World.new(

lib/mutant/range.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module Mutant
+  module Range
+    # Test if two ranges overlap
+    #
+    # @param [Range] left
+    # @param [Range] right
+    #
+    # @return [Boolean]
+    def self.overlap?(left, right)
+      left.end >= right.begin && right.end >= left.begin
+    end
+  end # Range
+end # end

spec/unit/mutant/range_spec.rb

@@ -0,0 +1,141 @@
+# frozen_string_literal: true
+
+describe Mutant::Range do
+  describe '.overlap?' do
+    def apply
+      described_class.overlap?(left, right)
+    end
+
+    context 'no overlap left before right' do
+      # |---|
+      #       |---|
+      let(:left)  { 1..2 }
+      let(:right) { 3..4 }
+
+      it 'returns false' do
+        expect(apply).to be(false)
+      end
+    end
+
+    context 'no overlap right before left' do
+      #       |---|
+      # |---|
+      let(:left)  { 3..4 }
+      let(:right) { 1..2 }
+
+      it 'returns false' do
+        expect(apply).to be(false)
+      end
+    end
+
+    context 'left includes right' do
+      # |----------------|
+      #       |---|
+      let(:left)  { 1..4 }
+      let(:right) { 2..3 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'right includes left' do
+      #       |---|
+      # |----------------|
+      let(:left)  { 2..3 }
+      let(:right) { 1..4 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'right starts with left end' do
+      # |----|
+      #      |----|
+      let(:left)  { 1..2 }
+      let(:right) { 2..3 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'left starts with right end' do
+      #      |----|
+      # |----|
+      let(:left)  { 2..3 }
+      let(:right) { 1..2 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'left starts with right start' do
+      # |----|
+      # |---------|
+      let(:left)  { 1..2 }
+      let(:right) { 1..3 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'left starts with right start' do
+      # |---------|
+      # |----|
+      let(:left)  { 1..3 }
+      let(:right) { 1..2 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'left ends with right end' do
+      #      |----|
+      # |---------|
+      let(:left)  { 2..3 }
+      let(:right) { 1..3 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'right ends with left end' do
+      # |---------|
+      #      |----|
+      let(:left)  { 1..3 }
+      let(:right) { 2..3 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'left end intersects with right' do
+      # |---------|
+      #      |----------|
+      let(:left)  { 1..3 }
+      let(:right) { 2..4 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+
+    context 'right end intersects with left' do
+      #      |----------|
+      # |---------|
+      let(:left)  { 2..4 }
+      let(:right) { 1..2 }
+
+      it 'returns true' do
+        expect(apply).to be(true)
+      end
+    end
+  end
+end