From bc5e0924d21dbbb95889d49c7ff3c0fa53f51cfb Mon Sep 17 00:00:00 2001
From: Taus <tausbn@github.com>
Date: Wed, 13 Oct 2021 12:27:20 +0000
Subject: [PATCH] Add tests for "implicit `this`"

---
 ql/test/queries/style/ImplicitThis/Bad.qll       | 11 +++++++++++
 ql/test/queries/style/ImplicitThis/Good.qll      | 16 ++++++++++++++++
 .../style/ImplicitThis/ImplicitThis.expected     |  1 +
 .../style/ImplicitThis/ImplicitThis.qlref        |  1 +
 ql/test/queries/style/ImplicitThis/Okay.qll      | 13 +++++++++++++
 5 files changed, 42 insertions(+)
 create mode 100644 ql/test/queries/style/ImplicitThis/Bad.qll
 create mode 100644 ql/test/queries/style/ImplicitThis/Good.qll
 create mode 100644 ql/test/queries/style/ImplicitThis/ImplicitThis.expected
 create mode 100644 ql/test/queries/style/ImplicitThis/ImplicitThis.qlref
 create mode 100644 ql/test/queries/style/ImplicitThis/Okay.qll

diff --git a/ql/test/queries/style/ImplicitThis/Bad.qll b/ql/test/queries/style/ImplicitThis/Bad.qll
new file mode 100644
index 00000000000..97b51284acc
--- /dev/null
+++ b/ql/test/queries/style/ImplicitThis/Bad.qll
@@ -0,0 +1,11 @@
+import ql
+
+class Foo extends string {
+  Foo() { this = "hello" }
+
+  string getBar() { result = "bar" }
+
+  string getBarWithThis() { result = this.getBar() }
+
+  string getBarWithoutThis() { result = getBar() }
+}
diff --git a/ql/test/queries/style/ImplicitThis/Good.qll b/ql/test/queries/style/ImplicitThis/Good.qll
new file mode 100644
index 00000000000..95b5f17f1de
--- /dev/null
+++ b/ql/test/queries/style/ImplicitThis/Good.qll
@@ -0,0 +1,16 @@
+import ql
+
+class Foo extends string {
+  Foo() { this = "hello" }
+
+  string getBar() { result = "bar" }
+
+  string getBarWithThis() { result = this.getBar() }
+
+  /* Okay because not a member predicate. */
+  string getBaz() { result = Baz::baz() }
+}
+
+module Baz {
+  string baz() { result = "baz" }
+}
diff --git a/ql/test/queries/style/ImplicitThis/ImplicitThis.expected b/ql/test/queries/style/ImplicitThis/ImplicitThis.expected
new file mode 100644
index 00000000000..fa3adbaf992
--- /dev/null
+++ b/ql/test/queries/style/ImplicitThis/ImplicitThis.expected
@@ -0,0 +1 @@
+| Bad.qll:10:41:10:48 | PredicateCall | Use of implicit `this`. |
diff --git a/ql/test/queries/style/ImplicitThis/ImplicitThis.qlref b/ql/test/queries/style/ImplicitThis/ImplicitThis.qlref
new file mode 100644
index 00000000000..0bdcd3b4b5b
--- /dev/null
+++ b/ql/test/queries/style/ImplicitThis/ImplicitThis.qlref
@@ -0,0 +1 @@
+queries/style/ImplicitThis.ql
diff --git a/ql/test/queries/style/ImplicitThis/Okay.qll b/ql/test/queries/style/ImplicitThis/Okay.qll
new file mode 100644
index 00000000000..37c9dd4ab2a
--- /dev/null
+++ b/ql/test/queries/style/ImplicitThis/Okay.qll
@@ -0,0 +1,13 @@
+import ql
+
+class Foo extends string {
+  Foo() { this = "hello" }
+
+  string getBar() { result = "bar" }
+
+  /* Okay, because we don't write `this.some_method` anywhere */
+  string getBarWithoutThis() { result = getBar() }
+
+  /* Okay, because this is the only way to cast `this`. */
+  string useThisWithInlineCast() { result = this.(string).toUpperCase() }
+}