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require "spec_helper"
describe AVLTree do
subject { AVLTree.new }
context "when empty" do
it "should have a size of 0" do
expect(subject.size).to eq(0)
end
it "should have have a height of 0" do
expect(subject.height).to eq(0)
end
end
context "when a single item is added" do
before :each do
subject.push("A")
end
it "should have a size of 1" do
expect(subject.size).to eq(1)
end
it "should have a height of 1" do
expect(subject.height).to eq(1)
end
end
context "when two items are added" do
before :each do
subject.add("a")
subject.add("b")
end
it "should have a size of 2" do
expect(subject.size).to eq(2)
end
it "should have a height of 2" do
expect(subject.height).to eq(2)
end
end
context "when a balanced tree has 3 items" do
before :each do
subject.add("b")
subject.add("a")
subject.add("c")
end
it "should have a size of 3" do
expect(subject.size).to eq(3)
end
it "should have a height of 2" do
expect(subject.height).to eq(2)
end
end
context "when the tree is unbalanced" do
context "with a right-right case" do
before :each do
subject.add("a")
subject.add("b")
subject.add("c")
end
it "should re-balance it self" do
expect(subject.height).to eq(2)
end
it "should have a new root" do
expect(subject.root.data).to eq("b")
end
it "should change the left side" do
expect(subject.root.left.data).to eq("a")
end
it "should change the right side" do
expect(subject.root.right.data).to eq("c")
end
end
context "with a left-left case" do
before :each do
subject.add("c")
subject.add("b")
subject.add("a")
end
it "should re-balance it self" do
expect(subject.height).to eq(2)
end
it "should have a new root" do
expect(subject.root.data).to eq("b")
end
it "should change the left side" do
expect(subject.root.left.data).to eq("a")
end
it "should change the right side" do
expect(subject.root.right.data).to eq("c")
end
end
context "with a left-right case" do
before :each do
subject.add(5)
subject.add(3)
subject.add(4)
end
it "should adjust the height" do
expect(subject.height).to eq(2)
end
it "should have a new root" do
expect(subject.root.data).to eq(4)
end
it "should have a proper left side" do
expect(subject.root.left.data).to eq(3)
end
it "should have a proper right side" do
expect(subject.root.right.data).to eq(5)
end
end
context "with a right-left case" do
before :each do
subject.add(3)
subject.add(5)
subject.add(4)
end
it "should adjust the height" do
expect(subject.height).to eq(2)
end
it "should have a new root" do
expect(subject.root.data).to eq(4)
end
it "should have a proper left side" do
expect(subject.root.left.data).to eq(3)
end
it "should have a proper right side" do
expect(subject.root.right.data).to eq(5)
end
end
end
end
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