Fixed unicode strings in JS

tests/js/tstringitems.nim

@@ -3,22 +3,76 @@ discard """
 Hello'''
 """
 
-# bug #2581
+block: # bug #2581
+  const someVars = [ "Hello" ]
+  var someVars2 = [ "Hello" ]
 
-const someVars = [ "Hello" ]
-var someVars2 = [ "Hello" ]
+  proc getSomeVar: string =
+      for i in someVars:
+          if i == "Hello":
+              result = i
+              break
 
-proc getSomeVar: string =
-    for i in someVars:
-        if i == "Hello":
-            result = i
-            break
+  proc getSomeVar2: string =
+      for i in someVars2:
+          if i == "Hello":
+              result = i
+              break
 
-proc getSomeVar2: string =
-    for i in someVars2:
-        if i == "Hello":
-            result = i
-            break
+  echo getSomeVar()
+  echo getSomeVar2()
 
-echo getSomeVar()
-echo getSomeVar2()
+block: # Test compile-time binary data generation, invalid unicode
+  proc signatureMaker(): string {. compiletime .} =
+    const signatureBytes = [137, 80, 78, 71, 13, 10, 26, 10]
+    result = ""
+    for c in signatureBytes: result.add chr(c)
+
+  const cSig = signatureMaker()
+
+  var rSig = newString(8)
+  rSig[0] = chr(137)
+  rSig[1] = chr(80)
+  rSig[2] = chr(78)
+  rSig[3] = chr(71)
+  rSig[4] = chr(13)
+  rSig[5] = chr(10)
+  rSig[6] = chr(26)
+  rSig[7] = chr(10)
+
+  doAssert(rSig == cSig)
+
+block: # Test unicode strings
+  const constStr = "Привет!"
+  var jsStr : cstring
+  {.emit: """`jsStr`[0] = "Привет!";""".}
+
+  doAssert($jsStr == constStr)
+  var runtimeStr = "При"
+  runtimeStr &= "вет!"
+
+  doAssert(runtimeStr == constStr)
+
+block: # Conversions from/to cstring
+  proc stringSaysHelloInRussian(s: cstring): bool =
+    {.emit: """`result` = (`s` === "Привет!");""".}
+
+  doAssert(stringSaysHelloInRussian("Привет!"))
+
+  const constStr = "Привет!"
+  doAssert(stringSaysHelloInRussian(constStr))
+
+  var rtStr = "Привет!"
+  doAssert(stringSaysHelloInRussian(rtStr))
+
+block: # String case of
+  const constStr = "Привет!"
+  var s = "Привет!"
+
+  case s
+  of constStr: discard
+  else: doAssert(false)
+
+  case s
+  of "Привет!": discard
+  else: doAssert(false)