better use if-then-else then && || in shell script

* Fix the "01-test" file with shellcheck

Its code has a problem SC2015.
https://github.com/koalaman/shellcheck/wiki/SC2015

* Add the ".idea" file in ".gitignore"

".idea" file is created by IDE made by IntelliJ IDEA

* Removed .idea folder

* Update 01-test

Co-authored-by: Jens Getreu <getreu@web.de>

.gitignore

@@ -6,3 +6,4 @@ target
 *.1.gz
 .vscode/
 tests/functional/output
+.idea

01-test

@@ -2,9 +2,12 @@
 
 # Unit testing
 
-cargo test \
-    && echo Cargo test succeeded. \
-    || ( echo Cargo test failed. && exit 1 )
+if cargo test
+then
+  echo Cargo test succeeded.
+else
+  ( echo Cargo test failed. && exit 1 )
+fi
 
 
 # Functional tests
@@ -17,23 +20,32 @@ cargo build
 ../../target/debug/stringsext -q 16 -g 63 -tx -a All-Ctrl -u Common \
     -e UTF-8 -e utf-16le -e utf-16be input1  > output
 
-diff output expected_output1 \
-    && echo Commandline test 1 succeeded. \
-    || ( echo Commandline test 1 failed. && exit 2 )
+if diff output expected_output1
+then
+    echo Commandline test 1 succeeded.
+else
+    ( echo Commandline test 1 failed. && exit 2 )
+fi
 
 # We search for `:`.
 ../../target/debug/stringsext -n 10 -q 32 -g 58 -tx -a All-Ctrl -u Common \
     -e UTF-8 -e utf-16le -e utf-16be input1 input2  > output
 
-diff output expected_output2 \
-    && echo Commandline test 2 succeeded. \
-    || ( echo Commandline test 2 failed. && exit 3 )
+if diff output expected_output2
+then
+    echo Commandline test 2 succeeded.
+else
+    ( echo Commandline test 2 failed. && exit 3 )
+fi
 
 # We search for nothing. Do we get nothing?
 ../../target/debug/stringsext -q 32 -tx -a None -u None \
     -e UTF-8 -e utf-16le -e utf-16be input1 input2  > output
 
-diff output expected_output3 \
-    && echo Commandline test 3 succeeded. \
-    || ( echo Commandline test 3 failed. && exit 4 )
+if diff output expected_output3
+then
+    echo Commandline test 3 succeeded.
+else
+    ( echo Commandline test 3 failed. && exit 4 )
+fi