Fix tests

Library/Homebrew/test/api/cask_spec.rb

@@ -41,4 +41,14 @@ describe Homebrew::API::Cask do
       expect(casks_output).to eq casks_hash
     end
   end
+
+  describe "::fetch_source" do
+    it "fetches the source of a cask (defaulting to master when no `git_head` is passed)" do
+      curl_output = OpenStruct.new(stdout: "foo", success?: true)
+      expect(Utils::Curl).to receive(:curl_output)
+        .with("--fail", "https://raw.githubusercontent.com/Homebrew/homebrew-cask/master/Casks/foo.rb", max_time: 5)
+        .and_return(curl_output)
+      described_class.fetch_source("foo", git_head: nil)
+    end
+  end
 end

Library/Homebrew/test/api_spec.rb

@@ -21,12 +21,6 @@ describe Homebrew::API do
   end
 
   describe "::fetch" do
-    it "fetches a text file" do
-      mock_curl_output stdout: text
-      fetched_text = described_class.fetch("foo.txt", json: false)
-      expect(fetched_text).to eq text
-    end
-
     it "fetches a JSON file" do
       mock_curl_output stdout: json
       fetched_json = described_class.fetch("foo.json")
@@ -70,4 +64,19 @@ describe Homebrew::API do
       }.to raise_error(SystemExit)
     end
   end
+
+  describe "::fetch_file_source" do
+    it "fetches a file" do
+      mock_curl_output stdout: json
+      fetched_json = described_class.fetch_file_source("foo.json", repo: "Homebrew/homebrew-core", git_head: "master")
+      expect(fetched_json).to eq json
+    end
+
+    it "raises an error if the file does not exist" do
+      mock_curl_output success: false
+      expect {
+        described_class.fetch_file_source("bar.txt", repo: "Homebrew/homebrew-core", git_head: "master")
+      }.to raise_error(ArgumentError, /No file found/)
+    end
+  end
 end