1 files changed, 81 insertions, 0 deletions
diff --git a/spec/ruby/core/array/bsearch_index_spec.rb b/spec/ruby/core/array/bsearch_index_spec.rb
new file mode 100644
index 0000000000..e1d5eb66bb
--- /dev/null
+++ b/spec/ruby/core/array/bsearch_index_spec.rb
@@ -0,0 +1,81 @@
+require_relative '../../spec_helper'
+require_relative '../enumerable/shared/enumeratorized'
+
+describe "Array#bsearch_index" do
+  context "when not passed a block" do
+    before :each do
+      @enum = [1, 2, 42, 100, 666].bsearch_index
+    end
+
+    it "returns an Enumerator" do
+      @enum.should.instance_of?(Enumerator)
+    end
+
+    it "returns an Enumerator with unknown size" do
+      @enum.size.should == nil
+    end
+
+    it "returns index of element when block condition is satisfied" do
+      @enum.each { |x| x >= 33 }.should == 2
+    end
+  end
+
+  it "raises a TypeError when block returns a String" do
+    -> { [1, 2, 3].bsearch_index { "not ok" } }.should.raise(TypeError)
+  end
+
+  it "returns nil when block is empty" do
+    [1, 2, 3].bsearch_index {}.should == nil
+  end
+
+  context "minimum mode" do
+    before :each do
+      @array = [0, 4, 7, 10, 12]
+    end
+
+    it "returns index of first element which satisfies the block" do
+      @array.bsearch_index { |x| x >= 4 }.should == 1
+      @array.bsearch_index { |x| x >= 6 }.should == 2
+      @array.bsearch_index { |x| x >= -1 }.should == 0
+    end
+
+    it "returns nil when block condition is never satisfied" do
+      @array.bsearch_index { false }.should == nil
+      @array.bsearch_index { |x| x >= 100 }.should == nil
+    end
+  end
+
+  context "find any mode" do
+    before :each do
+      @array = [0, 4, 7, 10, 12]
+    end
+
+    it "returns the index of any matched elements where element is between 4 <= x < 8" do
+      [1, 2].should.include?(@array.bsearch_index { |x| 1 - x / 4 })
+    end
+
+    it "returns the index of any matched elements where element is between 8 <= x < 10" do
+      @array.bsearch_index { |x| 4 - x / 2 }.should == nil
+    end
+
+    it "returns nil when block never returns 0" do
+      @array.bsearch_index { |x| 1 }.should == nil
+      @array.bsearch_index { |x| -1 }.should == nil
+    end
+
+    context "magnitude does not effect the result" do
+      it "returns the index of any matched elements where element is between 4n <= xn < 8n" do
+        [1, 2].should.include?(@array.bsearch_index { |x| (1 - x / 4) * (2**100) })
+      end
+
+      it "returns nil when block never returns 0" do
+        @array.bsearch_index { |x| 1 * (2**100) }.should == nil
+        @array.bsearch_index { |x| (-1) * (2**100) }.should == nil
+      end
+
+      it "handles values from Integer#coerce" do
+        [1, 2].should.include?(@array.bsearch_index { |x| (2**100).coerce((1 - x / 4) * (2**100)).first })
+      end
+    end
+  end
+end