RSpec - 匹配器

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如果你還記得我們最初的 Hello World 示例，它包含一行如下所示的程式碼 -

expect(message).to eq "Hello World!"

關鍵字 eql 是一個 **RSpec** “匹配器”。在這裡，我們將介紹 RSpec 中的其他型別的匹配器。

相等性/同一性匹配器

用於測試物件或值相等性的匹配器。

示例

describe "An example of the equality Matchers" do 

   it "should show how the equality Matchers work" do 
      a = "test string" 
      b = a 
      
      # The following Expectations will all pass 
      expect(a).to eq "test string" 
      expect(a).to eql "test string" 
      expect(a).to be b 
      expect(a).to equal b 
   end
   
end

當以上程式碼執行時，將產生以下輸出。秒數在您的計算機上可能略有不同 -

.
Finished in 0.036 seconds (files took 0.11901 seconds to load)
1 example, 0 failures

比較匹配器

用於比較兩個值的匹配器。

示例

describe "An example of the comparison Matchers" do

   it "should show how the comparison Matchers work" do
      a = 1
      b = 2
      c = 3		
      d = 'test string'
      
      # The following Expectations will all pass
      expect(b).to be > a
      expect(a).to be >= a 
      expect(a).to be < b 
      expect(b).to be <= b 
      expect(c).to be_between(1,3).inclusive 
      expect(b).to be_between(1,3).exclusive 
      expect(d).to match /TEST/i 
   end
   
end

當以上程式碼執行時，將產生以下輸出。秒數在您的計算機上可能略有不同 -

. 
Finished in 0.013 seconds (files took 0.11801 seconds to load) 
1 example, 0 failures

類/型別匹配器

用於測試物件型別或類的匹配器。

示例

describe "An example of the type/class Matchers" do
 
   it "should show how the type/class Matchers work" do
      x = 1 
      y = 3.14 
      z = 'test string' 
      
      # The following Expectations will all pass
      expect(x).to be_instance_of Fixnum 
      expect(y).to be_kind_of Numeric 
      expect(z).to respond_to(:length) 
   end
   
end

當以上程式碼執行時，將產生以下輸出。秒數在您的計算機上可能略有不同 -

. 
Finished in 0.002 seconds (files took 0.12201 seconds to load) 
1 example, 0 failures

真/假/空匹配器

用於測試值是否為真、假或空。

示例

describe "An example of the true/false/nil Matchers" do
   it "should show how the true/false/nil Matchers work" do
      x = true 
      y = false 
      z = nil 
      a = "test string" 
      
      # The following Expectations will all pass
      expect(x).to be true 
      expect(y).to be false 
      expect(a).to be_truthy 
      expect(z).to be_falsey 
      expect(z).to be_nil 
   end 
end

當以上程式碼執行時，將產生以下輸出。秒數在您的計算機上可能略有不同 -

. 
Finished in 0.003 seconds (files took 0.12301 seconds to load) 
1 example, 0 failures

用於測試程式碼塊何時引發錯誤的匹配器。

錯誤匹配器

示例

將以下程式碼儲存到名為 **error_matcher_spec.rb** 的檔案中，並使用以下命令執行它 - **rspec error_matcher_spec.rb**。

describe "An example of the error Matchers" do 
   it "should show how the error Matchers work" do 
      
      # The following Expectations will all pass 
      expect { 1/0 }.to raise_error(ZeroDivisionError)
      expect { 1/0 }.to raise_error("divided by 0") 
      expect { 1/0 }.to raise_error("divided by 0", ZeroDivisionError) 
   end 
end

當以上程式碼執行時，將產生以下輸出。秒數在您的計算機上可能略有不同 -

. 
Finished in 0.002 seconds (files took 0.12101 seconds to load) 
1 example, 0 failures