1 files changed, 27 insertions, 24 deletions
diff --git a/spec/ruby/library/matrix/permutation_spec.rb b/spec/ruby/library/matrix/permutation_spec.rb
index 825a9d982c..ed8edad755 100644
--- a/spec/ruby/library/matrix/permutation_spec.rb
+++ b/spec/ruby/library/matrix/permutation_spec.rb
@@ -1,32 +1,35 @@
 require_relative '../../spec_helper'
-require 'matrix'
 
-describe "Matrix#permutation?" do
-  it "returns true for a permutation Matrix" do
-    Matrix[[0, 1, 0], [0, 0, 1], [1, 0, 0]].permutation?.should be_true
-  end
+ruby_version_is ""..."3.1" do
+  require 'matrix'
 
-  it "returns false for a non permutation square Matrix" do
-    Matrix[[0, 1], [0, 0]].permutation?.should be_false
-    Matrix[[-1, 0], [0, -1]].permutation?.should be_false
-    Matrix[[1, 0], [1, 0]].permutation?.should be_false
-    Matrix[[1, 0], [1, 1]].permutation?.should be_false
-  end
+  describe "Matrix#permutation?" do
+    it "returns true for a permutation Matrix" do
+      Matrix[[0, 1, 0], [0, 0, 1], [1, 0, 0]].permutation?.should be_true
+    end
 
-  it "returns true for an empty 0x0 matrix" do
-    Matrix.empty(0,0).permutation?.should be_true
-  end
+    it "returns false for a non permutation square Matrix" do
+      Matrix[[0, 1], [0, 0]].permutation?.should be_false
+      Matrix[[-1, 0], [0, -1]].permutation?.should be_false
+      Matrix[[1, 0], [1, 0]].permutation?.should be_false
+      Matrix[[1, 0], [1, 1]].permutation?.should be_false
+    end
+
+    it "returns true for an empty 0x0 matrix" do
+      Matrix.empty(0,0).permutation?.should be_true
+    end
 
-  it "raises an error for rectangular matrices" do
-    [
-      Matrix[[0], [0]],
-      Matrix[[0, 0]],
-      Matrix.empty(0, 2),
-      Matrix.empty(2, 0),
-    ].each do |rectangular_matrix|
-      -> {
-        rectangular_matrix.permutation?
-      }.should raise_error(Matrix::ErrDimensionMismatch)
+    it "raises an error for rectangular matrices" do
+      [
+        Matrix[[0], [0]],
+        Matrix[[0, 0]],
+        Matrix.empty(0, 2),
+        Matrix.empty(2, 0),
+      ].each do |rectangular_matrix|
+        -> {
+          rectangular_matrix.permutation?
+        }.should raise_error(Matrix::ErrDimensionMismatch)
+      end
     end
   end
 end