From c054cbb64d55cb8cd456b6def155e86fa9da5016 Mon Sep 17 00:00:00 2001
From: Thomas den Hollander <ThomasdenH@users.noreply.github.com>
Date: Thu, 10 Jan 2019 19:39:43 +0100
Subject: [PATCH] Fix strict-type-predicate for unknown (#4444)

* Add tests for strict-type-predicates and unknown

* Fix unknown with strict-type-predicate

* Fix unknown literal
---
 src/rules/strictTypePredicatesRule.ts         |  7 +++-
 .../strict-null-checks/test.ts.lint           |  3 ++
 .../unknown/test.ts.lint                      | 42 +++++++++++++++++++
 .../unknown/tsconfig.json                     |  5 +++
 .../unknown/tslint.json                       |  5 +++
 5 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 test/rules/strict-type-predicates/unknown/test.ts.lint
 create mode 100644 test/rules/strict-type-predicates/unknown/tsconfig.json
 create mode 100644 test/rules/strict-type-predicates/unknown/tslint.json

diff --git a/src/rules/strictTypePredicatesRule.ts b/src/rules/strictTypePredicatesRule.ts
index bd07d69bd58..2a878137f2a 100644
--- a/src/rules/strictTypePredicatesRule.ts
+++ b/src/rules/strictTypePredicatesRule.ts
@@ -99,7 +99,12 @@ function walk(ctx: Lint.WalkContext<void>, checker: ts.TypeChecker): void {
 
         const exprType = checker.getTypeAtLocation(exprPred.expression);
         // TODO: could use checker.getBaseConstraintOfType to help with type parameters, but it's not publicly exposed.
-        if (isTypeFlagSet(exprType, ts.TypeFlags.Any | ts.TypeFlags.TypeParameter)) {
+        if (
+            isTypeFlagSet(
+                exprType,
+                ts.TypeFlags.Any | ts.TypeFlags.TypeParameter | ts.TypeFlags.Unknown,
+            )
+        ) {
             return;
         }
 
diff --git a/test/rules/strict-type-predicates/strict-null-checks/test.ts.lint b/test/rules/strict-type-predicates/strict-null-checks/test.ts.lint
index 57c624c8a4d..2f45d333a2f 100644
--- a/test/rules/strict-type-predicates/strict-null-checks/test.ts.lint
+++ b/test/rules/strict-type-predicates/strict-null-checks/test.ts.lint
@@ -194,6 +194,9 @@ declare function get<T>(): T;
     typeof get<string | number>() === `stirng`;
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [typeof]
 
+    typeof get<any>() === "unknown";
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [typeof]
+
     let a: string, b: string;
     typeof a === typeof b;
     typeof a === b;
diff --git a/test/rules/strict-type-predicates/unknown/test.ts.lint b/test/rules/strict-type-predicates/unknown/test.ts.lint
new file mode 100644
index 00000000000..40dd5d0da99
--- /dev/null
+++ b/test/rules/strict-type-predicates/unknown/test.ts.lint
@@ -0,0 +1,42 @@
+[typescript]: >= 3.0.0
+
+declare function get<T>(): T;
+
+// typeof
+{
+    typeof get<unknown>() === "undefined";
+    typeof get<unknown>() === "boolean";
+    typeof get<unknown>() === "number";
+    typeof get<unknown>() === "string";
+    typeof get<unknown>() === "symbol";
+    typeof get<unknown>() === "function";
+    typeof get<unknown>() === "object";
+}
+
+// negation
+{
+    get<unknown>() !== null;
+    get<unknown>() !== undefined;
+}
+
+// reverse left/right
+{
+    "string" === typeof get<unknown>();
+
+    undefined === get<unknown>();
+}
+
+// type parameters
+{
+    function f<T>(t: T) {
+        typeof t === "boolean";
+    }
+}
+
+const body: unknown = 'test';
+if (typeof body === 'object')
+    console.log('a');
+
+let test: unknown = undefined;
+if (test !== undefined)
+    console.log('b');
diff --git a/test/rules/strict-type-predicates/unknown/tsconfig.json b/test/rules/strict-type-predicates/unknown/tsconfig.json
new file mode 100644
index 00000000000..1cc3bc85ee9
--- /dev/null
+++ b/test/rules/strict-type-predicates/unknown/tsconfig.json
@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "strictNullChecks": true
+    }
+}
\ No newline at end of file
diff --git a/test/rules/strict-type-predicates/unknown/tslint.json b/test/rules/strict-type-predicates/unknown/tslint.json
new file mode 100644
index 00000000000..bb5f9231e91
--- /dev/null
+++ b/test/rules/strict-type-predicates/unknown/tslint.json
@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "strict-type-predicates": true
+  }
+}