From b6925725ce3508194e456025c6ca779625e77f2b Mon Sep 17 00:00:00 2001
From: Iulia Dumitru <iuliadmtru@gmail.com>
Date: Sun, 1 Sep 2024 19:27:27 +0200
Subject: [PATCH] Add rule for `rand(Bool)` instead of `rand() < 0.5`

---
 rules/lang/best-practice/rand_bool.fixed.jl | 40 +++++++++++++++++++++
 rules/lang/best-practice/rand_bool.jl       | 40 +++++++++++++++++++++
 rules/lang/best-practice/rand_bool.yaml     | 23 ++++++++++++
 3 files changed, 103 insertions(+)
 create mode 100644 rules/lang/best-practice/rand_bool.fixed.jl
 create mode 100644 rules/lang/best-practice/rand_bool.jl
 create mode 100644 rules/lang/best-practice/rand_bool.yaml

diff --git a/rules/lang/best-practice/rand_bool.fixed.jl b/rules/lang/best-practice/rand_bool.fixed.jl
new file mode 100644
index 0000000..8dc1e25
--- /dev/null
+++ b/rules/lang/best-practice/rand_bool.fixed.jl
@@ -0,0 +1,40 @@
+#ruleid: rand-bool
+rand(Bool)
+
+function some_rand_function(x)
+    #ruleid: rand-bool
+    if rand(Bool)
+        println("Random")
+    end
+end
+
+#ok: rand-bool
+rand() < 0.7  # this is fine
+
+x = rand()
+#ruleid: rand-bool
+if rand(Bool)
+    do_something()
+else
+    do_something_else()
+end
+
+#ok: rand-bool
+y = ok()
+if y < 0.5
+    do_something()
+else
+    do_something_else()
+end
+
+#ruleid: rand-bool
+rand(Bool) && action()
+
+#ok: rand-bool
+flag = rand(Bool)
+
+#ruleid: rand-bool
+if some_flag && rand(Bool) || other_flag
+    println("Random")
+end
+
diff --git a/rules/lang/best-practice/rand_bool.jl b/rules/lang/best-practice/rand_bool.jl
new file mode 100644
index 0000000..2efa460
--- /dev/null
+++ b/rules/lang/best-practice/rand_bool.jl
@@ -0,0 +1,40 @@
+#ruleid: rand-bool
+rand() < 0.5
+
+function some_rand_function(x)
+    #ruleid: rand-bool
+    if rand() < 0.5
+        println("Random")
+    end
+end
+
+#ok: rand-bool
+rand() < 0.7  # this is fine
+
+x = rand()
+#ruleid: rand-bool
+if x < 0.5
+    do_something()
+else
+    do_something_else()
+end
+
+#ok: rand-bool
+y = ok()
+if y < 0.5
+    do_something()
+else
+    do_something_else()
+end
+
+#ruleid: rand-bool
+x < 0.5 && action()
+
+#ok: rand-bool
+flag = rand(Bool)
+
+#ruleid: rand-bool
+if some_flag && rand() < 0.5 || other_flag
+    println("Random")
+end
+
diff --git a/rules/lang/best-practice/rand_bool.yaml b/rules/lang/best-practice/rand_bool.yaml
new file mode 100644
index 0000000..f24341d
--- /dev/null
+++ b/rules/lang/best-practice/rand_bool.yaml
@@ -0,0 +1,23 @@
+rules:
+  - id: rand-bool
+    patterns:
+      - pattern-either:
+        - pattern: $RAND() < 0.5
+        - patterns:
+            - pattern-inside: |
+                $X = $RAND()
+                ...
+                <... $X < 0.5 ...>
+            - pattern: $X < 0.5
+      - metavariable-regex:
+          metavariable: $RAND
+          regex: '(Base.)?rand'
+    fix: rand(Bool)
+    message: To get a random Boolean, use `rand(Bool)`.
+    languages:
+      - julia
+    severity: WARNING
+    metadata:
+      category: best-practice
+      license: LGPL
+