add guide to readme

README.md

@@ -71,6 +71,67 @@ npm run test -- init.test.sh
 
 ---
 
+### Writing integration tests
+
+```bash
+# it is recommended to execute npm run test before reading this to get a general idea of the behavior
+
+# lets take a look at init.test.sh
+# the command should initialize a project inside the current directory
+# the test follows the classic Arrange-Act-Assert pattern
+
+# our files start with #!/bin/bash, which tells your terminal it should use bash to execute the file
+#!/bin/bash
+
+# source lets you use the content of a file
+# ex. INIT_FOLDER, TEMPLATE_FILES
+source ./packages/cudos-tests/integration-tests/vars.sh
+
+# echo prints out the strings that are passed to it
+# -n flag tells your terminal to stay on the same line after printing out the message
+echo -n 'cudos init...'
+
+# ARRANGE
+# mkdir creates a folder at the path specified in INIT_FOLDER variable
+# cd moves to the specified directory
+# && lets you execute the command that follows the && only if the first command is successful
+mkdir $INIT_FOLDER && cd $INIT_FOLDER
+
+# ACT
+# &> /dev/null hides the output of the command
+cudos init &> /dev/null
+
+# ASSERT
+# ls -R lists directory content.
+# `` executes the command placed inside and provides its output
+# we compare the output with the expected folder structure defined in TEMPLATE_FILES
+if [[ ! `ls -R` == $TEMPLATE_FILES ]]; then
+    # if the output doesn't match we print out a fail message
+    # FAILED variable defines a red colored message
+    # -e flag escapes special characters, we need it in order to have colored messages
+    # 1>&2 redirects the output to stderr
+    echo -e "$FAILED\nGenerated folder is invalid!" 1>&2
+
+    # we define a variable with status 1
+    # in bash status code 1 means the script was not successful
+    exit_status=1
+else
+    # otherwise we print pass message
+    echo -e $PASSED
+fi
+
+# we cleanup the files generated by the test
+# rm -r removes the specified directory
+rm -r ../$INIT_FOLDER &> /dev/null
+
+# we exit the script
+# if the test fails and exit_status is assigned on line40 the program will exit with status 1
+# otherwise the exit_status will be undefined and the program will exit without a status, which means it was successful
+exit $exit_status
+```
+
+---
+
 ### Network selection
 
 todo