Add Format Test Results As A JSON File as an RSpec TIL

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1338 TILs and counting..._
+_1339 TILs and counting..._
 
 ---
 
@@ -1020,6 +1020,7 @@ _1338 TILs and counting..._
 
 - [Check Specific Arguments To Received Method](rspec/check-specific-arguments-to-received-method.md)
 - [Find Minimal Set Of Tests Causing A Flicker](rspec/find-minimal-set-of-tests-causing-a-flicker.md)
+- [Format Test Results As A JSON File](rspec/format-test-results-as-a-json-file.md)
 - [Run Tests With Documentation Formatting](rspec/run-tests-with-documentation-formatting.md)
 - [Use Specific Cache Store In A Single Test](rspec/use-specific-cache-store-in-a-single-test.md)
 

rspec/format-test-results-as-a-json-file.md

@@ -0,0 +1,21 @@
+# Format Test Results As A JSON File
+
+The most common output format for RSpec test results is _progress_ which shows
+the dot (`.`) or `F` for each test pass and fail. RSpec supports other formats,
+including JSON.
+
+You'd typically want to use the JSON format when you want to programmatically
+work with the results. And the results would be most accessible if they ended
+up in a file.
+
+So, when formatting the results to JSON, we typically also want to specify an
+output file. We'll need to use two flags — `--format` and `--out`.
+
+```bash
+$ rspec --format json --out test_run_1.json
+```
+
+When this test run completes, we will have the results in JSON format in the
+newly created `test_run_1.json` file in the current directory.
+
+See `rspec --help` for more details.