diff --git a/test/clojure/core_test/subs.cljc b/test/clojure/core_test/subs.cljc
index 1c83480..58bc039 100644
--- a/test/clojure/core_test/subs.cljc
+++ b/test/clojure/core_test/subs.cljc
@@ -4,12 +4,26 @@
 
 (when-var-exists clojure.core/subs
   (deftest test-subs
+    (is (= "abcde" (subs "abcde" 0)))
+    (is (= "abcde" (subs "abcde" 0 5)))
+    (is (= "ab֎de" (subs "ab֎de" 0)))
+    (is (= "ab֎de" (subs "ab֎de" 0 5)))
     (is (= "bcde" (subs "abcde" 1)))
+    (is (= "bcde" (subs "֎bcde" 1)))
     (is (= "bcd" (subs "abcde" 1 4)))
+    (is (= "bcd" (subs "֎bcde" 1 4)))
     (is (= "abc" (subs "abcde" 0 3)))
+    (is (= "ab֎" (subs "ab֎de" 0 3)))
+    (is (= "" (subs "" 0 0)))
+    (is (= "" (subs "" 0)))
     (is (= "" (subs "abcde" 0 0)))
+    (is (= "" (subs "֎bcde" 0 0)))
     (is (= "" (subs "abcde" 5)))
+    (is (= "" (subs "abcd֎" 5)))
     (is (= "" (subs "abcde" 5 5)))
+    (is (= "" (subs "abcd֎" 5 5)))
+    (is (= "" (subs "abcde" 4 4)))
+    (is (= "" (subs "abc֎e" 4 4)))
     #?@(:cljs
         [(is (= "b" (subs "abcde" 2 1)))
          (is (= "bcde" (subs "abcde" 1 6)))
diff --git a/test/clojure/string_test/blank_qmark.cljc b/test/clojure/string_test/blank_qmark.cljc
new file mode 100644
index 0000000..52f6e25
--- /dev/null
+++ b/test/clojure/string_test/blank_qmark.cljc
@@ -0,0 +1,28 @@
+(ns clojure.string-test.blank-qmark
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/blank?
+  (deftest test-blank?
+    (is (true? (str/blank? "")))
+    (is (true? (str/blank? nil)))
+    (is (false? (str/blank? "֎")))
+    (testing "U+2007"
+      (is (#?(:cljs true? :default false?) (str/blank? " ")))
+      (is (#?(:cljs true? :default false?) (str/blank? "\u2007"))))
+    (is (true? (str/blank? "  ")))
+    (is (true? (str/blank? " \t ")))
+    #?(:cljs (do (is (true? (str/blank? (symbol ""))))
+                 (is (false? (str/blank? 'a))))
+       :default (is (thrown? #?(:clj Exception) (str/blank? (symbol "")))))
+    #?(:cljs (do (is (false? (str/blank? (keyword ""))))
+                 (is (false? (str/blank? :a))))
+       :default (is (thrown? #?(:clj Exception) (str/blank? (keyword "")))))
+    #?(:cljs (is (false? (str/blank? 1)))
+       :default (is (thrown? #?(:clj Exception) (str/blank? 1))))
+    #?(:cljs (do (is (true? (str/blank? \space)))
+                 (is (false? (str/blank? \a))))
+       :default (is (thrown? #?(:clj Exception) (str/blank? \space))))
+    (is (false? (str/blank? "nil")))
+    (is (false? (str/blank? " as df ")))))
diff --git a/test/clojure/string_test/capitalize.cljc b/test/clojure/string_test/capitalize.cljc
new file mode 100644
index 0000000..e48d0a4
--- /dev/null
+++ b/test/clojure/string_test/capitalize.cljc
@@ -0,0 +1,23 @@
+(ns clojure.string-test.capitalize
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/capitalize
+  (deftest test-capitalize
+    (is (thrown? #?(:cljs :default :clj Exception) (str/capitalize nil)))
+    #?(:cljs (do (is (thrown? :default (str/capitalize 1)))
+                 (is (thrown? :default (str/capitalize 'a)))
+                 (is (thrown? :default (str/capitalize 'a/a)))
+                 (is (thrown? :default (str/capitalize :a)))
+                 (is (thrown? :default (str/capitalize :a/a))))
+       :default (do (is (= "1" (str/capitalize 1)))
+                    (is (= "Asdf" (str/capitalize 'Asdf)))
+                    (is (= "Asdf/asdf" (str/capitalize 'asDf/aSdf)))
+                    (is (= ":asdf/asdf" (str/capitalize :asDf/aSdf)))))
+    (is (= "" (str/capitalize "")))
+    (is (= "A" (str/capitalize "a")))
+    (is (= "֎" (str/capitalize "֎")))
+    (is (= "A thing" (str/capitalize "a Thing")))
+    (is (= "A thing" (str/capitalize "A THING")))
+    (is (= "A thing" (str/capitalize "A thing")))))
diff --git a/test/clojure/string_test/ends_with_qmark.cljc b/test/clojure/string_test/ends_with_qmark.cljc
new file mode 100644
index 0000000..249c764
--- /dev/null
+++ b/test/clojure/string_test/ends_with_qmark.cljc
@@ -0,0 +1,26 @@
+(ns clojure.string-test.ends-with-qmark
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/ends-with?
+  (deftest test-ends-with?
+    (is (true? (str/ends-with? "" "")))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/ends-with? "" nil)))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/ends-with? nil "")))
+    #?(:cljs (do (is (false? (str/ends-with? "ab" :b)))
+                 (is (false? (str/ends-with? "ab" :a))))
+       :default (is (thrown? #?(:clj Exception) (str/ends-with? "ab" :b))))
+    #?(:cljs (is (false? (str/ends-with? "ab" 'b)))
+       :default (is (thrown? #?(:clj Exception) (str/ends-with? "ab" 'b))))
+    (is (#?(:cljs false? :default true?) (str/ends-with? 'ab "b")))
+    (is (false? (str/ends-with? 'ab "a")))
+    (is (#?(:cljs false? :default true?) (str/ends-with? :ab "b")))
+    (is (false? (str/ends-with? :ab "a")))
+    (is (false? (str/ends-with? "" "a")))
+    (is (true? (str/ends-with? "a-test" "")))
+    (is (true? (str/ends-with? "a-test֎" "֎")))
+    (is (true? (str/ends-with? "a-test" "t")))
+    (is (true? (str/ends-with? "a-test" "a-test")))
+    (is (false? (str/ends-with? "a-test" "s")))
+    (is (false? (str/ends-with? "a-test" "a")))))
diff --git a/test/clojure/string_test/escape.cljc b/test/clojure/string_test/escape.cljc
new file mode 100644
index 0000000..654fc2d
--- /dev/null
+++ b/test/clojure/string_test/escape.cljc
@@ -0,0 +1,17 @@
+(ns clojure.string-test.escape
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/escape
+  (deftest test-escape
+    (is (= "" (str/escape "" {})))
+    (is (= "" (str/escape "" {\c "C_C"})))
+    (is (= "A_Abc" (str/escape "abc" {\a "A_A"})))
+    (is (= "A_AbC_C" (str/escape "abc" {\a "A_A" \c "C_C"})))
+    (is (= "A_AbC_C" (str/escape "abc" {\a "A_A" \c "C_C" (int \a) 1 nil 'junk :garbage 42.42})))
+    (is (= "A_AbC_C" (str/escape "abc" {\a "A_A" \c "C_C"})))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/escape nil {\a "A_A" \c "C_C"})))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/escape 1 {\a "A_A" \c "C_C"})))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/escape 'a {\a "A_A" \c "C_C"})))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/escape :a {\a "A_A" \c "C_C"})))))
diff --git a/test/clojure/string_test/lower_case.cljc b/test/clojure/string_test/lower_case.cljc
new file mode 100644
index 0000000..1f922e2
--- /dev/null
+++ b/test/clojure/string_test/lower_case.cljc
@@ -0,0 +1,21 @@
+(ns clojure.string-test.lower-case
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/lower-case
+  (deftest test-lower-case
+    (is (thrown? #?(:cljs :default :clj Exception) (str/lower-case nil)))
+    (is (= "" (str/lower-case "")))
+    (is (= "֎" (str/lower-case "֎")))
+    (is (= "asdf" (str/lower-case "AsdF")))
+    (is (= "asdf" (str/lower-case "asdf")))
+    (let [s "ASDF"]
+      (is (= "asdf" (str/lower-case "ASDF")))
+      (is (= "ASDF" s) "original string mutated"))
+    #?(:cljs (is (thrown? :default (str/lower-case :ASDF)))
+       :default (is (= ":asdf" (str/lower-case :ASDF))))
+    #?(:cljs (is (thrown? :default (str/lower-case :ASDF/ASDF)))
+       :default (is (= ":asdf/asdf" (str/lower-case :ASDF/ASDF))))
+    #?(:cljs (is (thrown? :default (str/lower-case 'ASDF)))
+       :default (is (= "asdf" (str/lower-case 'ASDF))))))
diff --git a/test/clojure/string_test/reverse.cljc b/test/clojure/string_test/reverse.cljc
new file mode 100644
index 0000000..5b0730a
--- /dev/null
+++ b/test/clojure/string_test/reverse.cljc
@@ -0,0 +1,15 @@
+(ns clojure.string-test.reverse
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/reverse
+  (deftest test-reverse
+    (is (= "" (str/reverse "")))
+    (is (= "֎" (str/reverse "֎")))
+    (is (= "a֎" (str/reverse "֎a")))
+    (is (= "tset-a" (str/reverse "a-test")))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/reverse nil)))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/reverse 1)))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/reverse 'a-test)))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/reverse :a-test)))))
diff --git a/test/clojure/string_test/starts_with_qmark.cljc b/test/clojure/string_test/starts_with_qmark.cljc
new file mode 100644
index 0000000..2290aaa
--- /dev/null
+++ b/test/clojure/string_test/starts_with_qmark.cljc
@@ -0,0 +1,38 @@
+(ns clojure.string-test.starts-with-qmark
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/starts-with?
+  (deftest test-starts-with?
+    (is (true? (str/starts-with? "" "")))
+    #?(:cljs (is (false? (str/starts-with? "" nil)))
+       :default (is (thrown? #?(:clj Exception) (str/starts-with? "" nil))))
+    (is (thrown? #?(:cljs :default :clj Exception) (str/starts-with? nil "")))
+    #?(:cljs (do (is (false? (str/starts-with? "ab" :a)))
+                 (is (true? (str/starts-with? ":ab" :a)))
+                 (is (false? (str/starts-with? "ab" :b))))
+       :default (is (thrown? #?(:clj Exception) (str/starts-with? "ab" :a))))
+    #?(:cljs (is (true? (str/starts-with? "ab" 'a)))
+       :default (is (thrown? #?(:clj Exception) (str/starts-with? "a" 'a))))
+    (is (false? (str/starts-with? "" "a")))
+    (is (true? (str/starts-with? "a-test" "")))
+    (is (true? (str/starts-with? "֎a-test" "֎")))
+    (is (true? (str/starts-with? "a-test" "a")))
+    (is (true? (str/starts-with? "a-test" "a-test")))
+    (is (false? (str/starts-with? "a-test" "-")))
+    (is (false? (str/starts-with? "a-test" "t")))
+    #?(:cljs (is (thrown? :default (str/starts-with? 'ab ":a")))
+       :default (do (is (false? (str/starts-with? 'ab "b")))
+                    (is (true? (str/starts-with? 'ab "a")))))
+    #?(:cljs (is (thrown? :default (str/starts-with? :ab ":a")))
+       :default (do (is (false? (str/starts-with? :ab "b")))
+                    (is (false? (str/starts-with? :ab "a")))
+                    (is (true? (str/starts-with? :ab ":a")))))
+    #?(:cljs (is (thrown? :default (str/starts-with? 'a/b ":a")))
+       :default (do (is (false? (str/starts-with? 'a/b "b")))
+                    (is (true? (str/starts-with? 'a/b "a")))))
+    #?(:cljs (is (thrown? :default (str/starts-with? :a/b ":a")))
+       :default (do (is (false? (str/starts-with? :a/b "b")))
+                    (is (false? (str/starts-with? :a/b "a")))
+                    (is (true? (str/starts-with? :a/b ":a")))))))
diff --git a/test/clojure/string_test/upper_case.cljc b/test/clojure/string_test/upper_case.cljc
new file mode 100644
index 0000000..6150999
--- /dev/null
+++ b/test/clojure/string_test/upper_case.cljc
@@ -0,0 +1,23 @@
+(ns clojure.string-test.upper-case
+  (:require [clojure.string :as str]
+            [clojure.test :as t :refer [deftest testing is are]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer)  [when-var-exists]]))
+
+(when-var-exists str/upper-case
+  (deftest test-upper-case
+    (is (thrown? #?(:cljs :default :clj Exception) (str/upper-case nil)))
+    (is (= "" (str/upper-case "")))
+    (is (= "֎" (str/upper-case "֎")))
+    (is (= "ASDF" (str/upper-case "aSDf")))
+    (is (= "ASDF" (str/upper-case "ASDF")))
+    (let [s "asdf"]
+      (is (= "ASDF" (str/upper-case "asdf")))
+      (is (= "asdf" s) "original string mutated"))
+    #?(:cljs (is (thrown? :default (str/upper-case :asdf)))
+       :default (is (= ":ASDF" (str/upper-case :asdf))))
+    #?(:cljs (is (thrown? :default (str/upper-case :asdf/asdf)))
+       :default (is (= ":ASDF/ASDF" (str/upper-case :asdf/asdf))))
+    #?(:cljs (is (thrown? :default (str/upper-case 'asdf)))
+       :default (is (= "ASDF" (str/upper-case 'asdf))))
+    #?(:cljs (is (thrown? :default (str/upper-case 'asdf/asdf)))
+       :default (is (= "ASDF/ASDF" (str/upper-case 'asdf/asdf))))))