Fixes source extraction from docs.

docs/050-breaking-changes.rst

@@ -456,7 +456,7 @@ New version:
             // Throw is now disallowed.
             require(x > 100);
             int y = -3 >> 1;
-         // y == -2 (correct)
+            require(y == -2);
             do {
                 x += 1;
                 if (x > 10) continue;
@@ -473,7 +473,7 @@ New version:
 
         using address_make_payable for address;
         // Data location for 'arr' must be specified
-      function g(uint[] memory arr, bytes8 x, OtherContract otherContract, address unknownContract) public payable {
+        function g(uint[] memory /* arr */, bytes8 x, OtherContract otherContract, address unknownContract) public payable {
             // 'otherContract.transfer' is not provided.
             // Since the code of 'OtherContract' is known and has the fallback
             // function, address(otherContract) has type 'address payable'.

docs/contracts/visibility-and-getters.rst

@@ -158,13 +158,13 @@ to write a function, for example:
 
         // Getter function generated by the compiler
         /*
-    function myArray(uint i) returns (uint) {
+        function myArray(uint i) public view returns (uint) {
             return myArray[i];
         }
         */
 
         // function that returns entire array
-    function getArray() returns (uint[] memory) {
+        function getArray() public view returns (uint[] memory) {
             return myArray;
         }
     }

docs/security-considerations.rst

@@ -554,7 +554,7 @@ types.
 
     pragma solidity >=0.5.0;
     pragma experimental SMTChecker;
-   // This will not compile
+    // This will report a warning
     contract Aliasing
     {
         uint[] array;

scripts/isolate_tests.py

@@ -39,6 +39,7 @@ def extract_test_cases(path):
 # and abort a line not indented properly.
 def extract_docs_cases(path):
     inside = False
+    extractedLines = []
     tests = []
 
     # Collect all snippets of indented blocks
@@ -46,15 +47,23 @@ def extract_docs_cases(path):
         if l != '':
             if not inside and l.startswith(' '):
                 # start new test
-                tests += ['']
+                extractedLines += ['']
             inside = l.startswith(' ')
         if inside:
-            tests[-1] += l + '\n'
-    # Filter all tests that do not contain Solidity
-    return [
-        test for test in tests
-        if re.search(r'^    [ ]*(pragma solidity|contract |library |interface )', test, re.MULTILINE)
-    ]
+            extractedLines[-1] += l + '\n'
+
+    codeStart = "(pragma solidity|contract.*{|library.*{|interface.*{)"
+
+    # Filter all tests that do not contain Solidity or are intended incorrectly.
+    for lines in extractedLines:
+        if re.search(r'^\s{0,3}' + codeStart, lines, re.MULTILINE):
+            print("Intendation error in " + path + ":")
+            print(lines)
+            exit(1)
+        if re.search(r'^\s{4}' + codeStart, lines, re.MULTILINE):
+            tests.append(lines)
+
+    return tests
 
 def write_cases(f, tests):
     cleaned_filename = f.replace(".","_").replace("-","_").replace(" ","_").lower()