fix doctest = :fix with empty output

src/DocChecks.jl

@@ -431,6 +431,7 @@ function fix_doctest(result::Result, str, doc::Documents.Document)
     # construct the new code-snippet (without indent)
     # first part: everything up until the last index of the input string
     newcode = code[1:last(inputidx)]
+    isempty(result.output) && (newcode *= '\n') # issue #772
     # second part: the rest, with the old output replaced with the new one
     newcode *= replace(code[nextind(code, last(inputidx)):end], result.output => str, count = 1)
     # replace internal code block with the non-indented new code, needed if we come back

test/doctests/broken.jl

@@ -70,6 +70,11 @@ Int64[1, 2, 3, 4] * 2
 julia> println("  foobar")
   foobaz
 ```
+```jldoctest
+julia> 1 + 2
+
+julia> 3 + 4
+```
 """
 foo() = 1
 

test/doctests/broken.md

@@ -72,3 +72,8 @@ Int64[1, 2, 3, 4] * 2
 julia> println("  foobar")
   foobaz
 ```
+```jldoctest
+julia> 1 + 2
+
+julia> 3 + 4
+```

test/doctests/fixed.jl

@@ -70,6 +70,13 @@ Int64[1, 2, 3, 4] * 2
 julia> println("  foobar")
   foobar
 ```
+```jldoctest
+julia> 1 + 2
+3
+
+julia> 3 + 4
+7
+```
 """
 foo() = 1
 

test/doctests/fixed.md

@@ -72,3 +72,10 @@ Int64[1, 2, 3, 4] * 2
 julia> println("  foobar")
   foobar
 ```
+```jldoctest
+julia> 1 + 2
+3
+
+julia> 3 + 4
+7
+```