Handle EOF input from jq

spec/converters/simple_yaml_spec.cr

@@ -333,6 +333,14 @@ describe OQ::Converters::SimpleYAML do
           end
         end
       end
+
+      describe "when the jq filter doesn't return data" do
+        it "should return an empty string" do
+          run_binary(%([{"name":"foo"}]), args: ["-i", "simpleyaml", "-o", "simpleyaml", %<.[] | select(.name != "foo")>]) do |output|
+            output.should be_empty
+          end
+        end
+      end
     end
 
     describe Object do

spec/converters/xml_spec.cr

@@ -232,9 +232,8 @@ describe OQ::Converters::XML do
 
     describe "should raise if invalid" do
       it "should output correctly" do
-        run_binary(%(<root id="1<child/></root>), args: ["-i", "xml", "-c", "."]) do |_, status, error|
+        run_binary(%(<root id="1<child/></root>), args: ["-i", "xml", "-c", "."], success: false) do |_, _, error|
           error.should eq "oq error: Couldn't find end of Start Tag root\n"
-          status.exit_code.should eq 1
         end
       end
     end

spec/converters/yaml_spec.cr

@@ -409,6 +409,14 @@ describe OQ::Converters::YAML do
           end
         end
       end
+
+      describe "when the jq filter doesn't return data" do
+        it "should return an empty string" do
+          run_binary(%([{"name":"foo"}]), args: ["-i", "yaml", "-o", "yaml", %<.[] | select(.name != "foo")>]) do |output|
+            output.should be_empty
+          end
+        end
+      end
     end
 
     describe Object do

spec/oq_spec.cr

@@ -260,27 +260,24 @@ describe OQ do
 
   describe "when there is a jq error" do
     it "should return the error and correct exit code" do
-      run_binary(input: ARRAY_JSON_OBJECT, args: [".names | .[] | .name"]) do |_, status, error|
+      run_binary(input: ARRAY_JSON_OBJECT, args: [".names | .[] | .name"], success: false) do |_, _, error|
         error.should eq %(jq: error (at <stdin>:0): Cannot index number with string "name"\n)
-        status.exit_code.should eq 1
       end
     end
   end
 
   describe "with an invalid input format" do
     it "should return the error and correct exit code" do
-      run_binary(input: SIMPLE_JSON_OBJECT, args: ["-i", "foo"]) do |_, status, error|
+      run_binary(input: SIMPLE_JSON_OBJECT, args: ["-i", "foo"], success: false) do |_, _, error|
         error.should eq %(Invalid input format: 'foo'\n)
-        status.exit_code.should eq 1
       end
     end
   end
 
   describe "with an invalid output format" do
     it "should return the error and correct exit code" do
-      run_binary(input: SIMPLE_JSON_OBJECT, args: ["-o", "foo"]) do |_, status, error|
+      run_binary(input: SIMPLE_JSON_OBJECT, args: ["-o", "foo"], success: false) do |_, _, error|
         error.should eq %(Invalid output format: 'foo'\n)
-        status.exit_code.should eq 1
       end
     end
   end

spec/spec_helper.cr

@@ -2,11 +2,18 @@ require "spec"
 require "../src/oq"
 
 # Runs the the binary with the given *name* and *args*.
-def run_binary(input : String? = nil, name : String = "bin/oq", args : Array(String) = [] of String, &block : String, Process::Status, String -> Nil)
+def run_binary(input : String? = nil, name : String = "bin/oq", args : Array(String) = [] of String, *, success : Bool = true, file = __FILE__, line = __LINE__, & : String, Process::Status, String -> Nil)
   buffer_io = IO::Memory.new
   error_io = IO::Memory.new
   input_io = IO::Memory.new
   input_io << input if input
   status = Process.run(name, args, output: buffer_io, input: input_io.rewind, error: error_io)
+
+  if success
+    status.success?.should be_true, file: file, line: line
+  else
+    status.success?.should_not be_true, file: file, line: line
+  end
+
   yield buffer_io.to_s, status, error_io.to_s
 end

src/converters/yaml.cr

@@ -8,9 +8,23 @@ module OQ::Converters::YAML
 
   # ameba:disable Metrics/CyclomaticComplexity
   def serialize(input : IO, output : IO, **args) : Nil
-    json = ::JSON::PullParser.new input
+    # TODO: Remove this in favor of the .eof? check after
+    # https://github.com/crystal-lang/crystal/pull/10864 is released.
+    begin
+      json = ::JSON::PullParser.new input
+    rescue ex : ::JSON::ParseException
+      if (message = ex.message) && (message.includes? "Unexpected token: <EOF>")
+        return
+      end
+
+      raise ex
+    end
+
     yaml = ::YAML::Builder.new output
 
+    # Return early is there is no JSON to be read.
+    return if json.kind.eof?
+
     yaml.stream do
       yaml.document do
         loop do