Introduce skip_if

On can now skip some tests in the file if some condition is true.

README.adoc

@@ -41,6 +41,7 @@ _(by the way, the documentation you are reading is itself tested with bash-unit)
   You can specify several patterns by repeating this option
   for each pattern.
   Tests will appear in *bash_unit* output as _pending_.
+  (see also _skip_if_)
 
 *-r*::
   executes test cases in random order.
@@ -574,6 +575,33 @@ out> > bar
 doc:2:test_obvious_notmatching_with_assert_no_diff()
 ```
 
+== *skip_if* function
+
+    skip_if <condition> <pattern>
+
+If _condition_ is true, will skip all the tests in the current file which match the given _pattern_.
+
+This can be useful when one has tests that are dependent on system environment, for instance:
+
+```test
+skip_if "uname | grep Darwin" linux
+skip_if "uname | grep Linux" darwin
+
+test_linux_proc_exists() {
+  assert "ls /proc/" "there should exist /proc on Linux"
+}
+test_darwin_proc_does_not_exist() {
+  assert_fail "ls /proc/" "there should not exist /proc on Darwin"
+}
+```
+
+will output, on a Linux system:
+
+```output
+	Running test_darwin_proc_does_not_exist ... PENDING
+	Running test_linux_proc_exists ... SUCCESS
+```
+
 == *fake* function
 
     fake <command> [replacement code]

bash_unit

@@ -430,6 +430,16 @@ tap_format() {
   }
 }
 
+skip_if() {
+  local condition="$1"
+  local pattern="$2"
+  if eval $condition >/dev/null 2>&1
+  then
+    skip_pattern="${skip_pattern}${skip_pattern_separator}${pattern}"
+    skip_pattern_separator="|"
+  fi
+}
+
 output_format=text
 test_pattern=""
 test_pattern_separator=""

getting_started/tests/test_skipping

@@ -1,30 +1,27 @@
 # This test demonstrates some test skipping logic that
 # one can implement with bash_unit
 
-todo_will_always_be_siped() {
+todo_will_always_be_skipped() {
   fail "This test is always skipped"
 }
 
-if uname | grep Linux
-then
-  test_proc_exists() {
-    assert "ls /proc/" "there should exist /proc on Linux"
-  }
-  test_another_test_to_run_only_on_linux() {
-    assert "mkdir /tmp/foo/bar -p"
-  }
-fi
+skip_if "uname | grep Darwin" linux
+skip_if "uname | grep Linux" darwin
+
+test_linux_proc_exists() {
+  assert "ls /proc/" "there should exist /proc on Linux"
+}
+test_another_test_to_run_only_on_linux() {
+  assert "mkdir /tmp/foo/bar -p"
+}
 
 test_that_always_run() {
   assert true
 }
 
-if uname | grep Darwin
-then
-  test_proc_does_not_exist() {
-    assert_fail "ls /proc/" "there should not exist /proc on Darwin"
-  }
-  test_another_test_to_run_only_on_darwin() {
-    assert "mkdir -p /tmp/foo/bar"
-  }
-fi
+test_darwin_proc_does_not_exist() {
+  assert_fail "ls /proc/" "there should not exist /proc on Darwin"
+}
+test_another_test_to_run_only_on_darwin() {
+  assert "mkdir -p /tmp/foo/bar"
+}

tests/test_cli.sh

@@ -88,19 +88,26 @@ Overall result: SUCCESS" \
 test_do_not_run_skipped_tests() {
   assert "$BASH_UNIT -s two \
     <(echo 'test_one() { echo -n ; }
-            test_two() { fail ; }') \
+            test_two() { fail ; }
+            test_three() { fail ; }
+            skip_if true three
+            ') \
   "
 }
 
 test_skipped_tests_appear_in_output() {
   bash_unit_output=$($BASH_UNIT -s two \
     <(echo 'test_one() { echo -n ; }
-            test_two() { fail ; }') \
+            test_two() { fail ; }
+            test_three() { fail ; }
+            skip_if true three
+            ') \
     | "$SED" -e 's:/dev/fd/[0-9]*:test_file:' \
   )
 
   assert_equals "\
 Running tests in test_file
+	Running test_three ... PENDING
 	Running test_two ... PENDING
 	Running test_one ... SUCCESS
 Overall result: SUCCESS" \