Fix line numbers being wrong with macro expansion

Addresses https://github.com/icy-arctic-fox/spectator/issues/18

spec/line_number_spec.cr

@@ -0,0 +1,27 @@
+require "./spec_helper"
+
+Spectator.describe Spectator do
+  let(current_example) { ::Spectator::Harness.current.example }
+  subject(source) { current_example.source }
+
+  context "line numbers" do
+    subject { source.line }
+
+    it "match source code" do
+      is_expected.to eq(__LINE__ - 1)
+    end
+
+    it "handles multiple lines and examples" do
+      # Offset is important.
+      is_expected.to eq(__LINE__ - 2)
+    end
+  end
+
+  context "file names" do
+    subject { source.file }
+
+    it "match source code" do
+      is_expected.to eq(__FILE__)
+    end
+  end
+end

src/spectator/dsl/assertions.cr

@@ -45,7 +45,7 @@ module Spectator
     # expect(&.size).to eq(5)
     # ```
     # The method passed will always be evaluated on the subject.
-    macro expect(_source_file = __FILE__, _source_line = __LINE__, &block)
+    macro expect(&block)
       {% if block.is_a?(Nop) %}
         {% raise "Argument or block must be provided to expect" %}
       {% end %}
@@ -76,7 +76,7 @@ module Spectator
         {% raise "Unexpected block arguments in expect call" %}
       {% end %}
 
-      %source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
+      %source = ::Spectator::Source.new({{block.filename}}, {{block.line_number}})
       ::Spectator::Expectations::ExpectationPartial.new(%test_block, %source)
     end
 

src/spectator/dsl/examples.cr

@@ -3,7 +3,7 @@ require "../spec_builder"
 
 module Spectator
   module DSL
-    macro it(description = nil, _source_file = __FILE__, _source_line = __LINE__, &block)
+    macro it(description = nil, &block)
       {% if block.is_a?(Nop) %}
         {% if description.is_a?(Call) %}
           def %run
@@ -18,7 +18,7 @@ module Spectator
         end
       {% end %}
 
-      %source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
+      %source = ::Spectator::Source.new({{block.filename}}, {{block.line_number}})
       ::Spectator::SpecBuilder.add_example(
         {{description.is_a?(StringLiteral) || description.is_a?(StringInterpolation) || description.is_a?(NilLiteral) ? description : description.stringify}},
         %source,
@@ -30,7 +30,7 @@ module Spectator
       it({{description}}) {{block}}
     end
 
-    macro pending(description = nil, _source_file = __FILE__, _source_line = __LINE__, &block)
+    macro pending(description = nil, &block)
       {% if block.is_a?(Nop) %}
         {% if description.is_a?(Call) %}
           def %run
@@ -45,7 +45,7 @@ module Spectator
         end
       {% end %}
 
-      %source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
+      %source = ::Spectator::Source.new({{block.filename}}, {{block.line_number}})
       ::Spectator::SpecBuilder.add_pending_example(
         {{description.is_a?(StringLiteral) || description.is_a?(StringInterpolation) || description.is_a?(NilLiteral) ? description : description.stringify}},
         %source,

src/spectator/dsl/groups.cr

@@ -2,7 +2,7 @@ require "../spec_builder"
 
 module Spectator
   module DSL
-    macro context(what, _source_file = __FILE__, _source_line = __LINE__, &block)
+    macro context(what, &block)
       class Context%context < {{@type.id}}
         {%
           description = if what.is_a?(StringLiteral) || what.is_a?(StringInterpolation)
@@ -16,7 +16,7 @@ module Spectator
                         end
         %}
 
-        %source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
+        %source = ::Spectator::Source.new({{block.filename}}, {{block.line_number}})
         ::Spectator::SpecBuilder.start_group({{description}}, %source)
 
         # Oddly, `#resolve?` can return a constant's value, which isn't a TypeNode.
@@ -49,7 +49,7 @@ module Spectator
       context({{what}}) {{block}}
     end
 
-    macro sample(collection, count = nil, _source_file = __FILE__, _source_line = __LINE__, &block)
+    macro sample(collection, count = nil, &block)
       {% name = block.args.empty? ? :value.id : block.args.first.id %}
 
       def %collection
@@ -65,7 +65,7 @@ module Spectator
       end
 
       class Context%sample < {{@type.id}}
-        %source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
+        %source = ::Spectator::Source.new({{block.filename}}, {{block.line_number}})
         ::Spectator::SpecBuilder.start_sample_group({{collection.stringify}}, %source, :%sample, {{name.stringify}}) do |values|
           sample = {{@type.id}}.new(values)
           sample.%to_a
@@ -81,7 +81,7 @@ module Spectator
       end
     end
 
-    macro random_sample(collection, count = nil, _source_file = __FILE__, _source_line = __LINE__, &block)
+    macro random_sample(collection, count = nil, &block)
       {% name = block.args.empty? ? :value.id : block.args.first.id %}
 
       def %collection
@@ -97,7 +97,7 @@ module Spectator
       end
 
       class Context%sample < {{@type.id}}
-        %source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
+        %source = ::Spectator::Source.new({{block.filename}}, {{block.line_number}})
         ::Spectator::SpecBuilder.start_sample_group({{collection.stringify}}, %source, :%sample, {{name.stringify}}) do |values|
           sample = {{@type.id}}.new(values)
           collection = sample.%to_a