Change output format of failed #expect_raises in specs

Author: andrykonchin

spec/std/spec/expectations_spec.cr

@@ -172,5 +172,99 @@ describe "expectations" do
     it "pass if raises MyError" do
       expect_raises(Exception, "Ops") { raise Exception.new("Ops") }
     end
+
+    describe "failure message format" do
+      context "given string to compare with message" do
+        it "contains expected exception, actual exception and backtrace" do
+          expect_raises(Exception, "digits should be non-negative") do
+            raise IndexError.new("Index out of bounds")
+          end
+        rescue e : Spec::AssertionFailed
+          e.message.as(String).should contain(<<-MESSAGE)
+            Expected Exception with message containing: "digits should be non-negative"
+                 got IndexError with message: "Index out of bounds"
+            Backtrace:
+              # spec/std/spec/expectations_spec.cr:#{__LINE__ - 7}:13 in '->'
+            MESSAGE
+        else
+          raise "nothing is raised"
+        end
+
+        it "contains expected class, actual exception and backtrace when expected class does not match actial class" do
+          expect_raises(ArgumentError, "digits should be non-negative") do
+            raise IndexError.new("Index out of bounds")
+          end
+        rescue e : Spec::AssertionFailed
+          e.message.as(String).should contain(<<-MESSAGE)
+            Expected ArgumentError
+                 got IndexError with message: "Index out of bounds"
+            Backtrace:
+              # spec/std/spec/expectations_spec.cr:#{__LINE__ - 7}:13 in '->'
+            MESSAGE
+        else
+          raise "nothing is raised"
+        end
+
+        it "escapes expected and actual messages in the same way" do
+          expect_raises(Exception, %q(a\tb\nc)) do
+            raise %q(a\tb\nc).inspect
+          end
+        rescue e : Spec::AssertionFailed
+          e.message.as(String).should contain("Expected Exception with message containing: #{%q(a\tb\nc).inspect}")
+          e.message.as(String).should contain("got Exception with message: #{%q(a\tb\nc).inspect.inspect}")
+        else
+          raise "nothing is raised"
+        end
+      end
+
+      context "given regex to match a message" do
+        it "contains expected exception, actual exception and backtrace" do
+          expect_raises(Exception, /digits should be non-negative/) do
+            raise IndexError.new("Index out of bounds")
+          end
+        rescue e : Spec::AssertionFailed
+          e.message.as(String).should contain(<<-MESSAGE)
+            Expected Exception with message matching: /digits should be non-negative/
+                 got IndexError with message: "Index out of bounds"
+            Backtrace:
+              # spec/std/spec/expectations_spec.cr:#{__LINE__ - 7}:13 in '->'
+            MESSAGE
+        else
+          raise "nothing is raised"
+        end
+
+        it "contains expected class, actual exception and backtrace when expected class does not match actial class" do
+          expect_raises(ArgumentError, /digits should be non-negative/) do
+            raise IndexError.new("Index out of bounds")
+          end
+        rescue e : Spec::AssertionFailed
+          e.message.as(String).should contain(<<-MESSAGE)
+            Expected ArgumentError
+                 got IndexError with message: "Index out of bounds"
+            Backtrace:
+              # spec/std/spec/expectations_spec.cr:#{__LINE__ - 7}:13 in '->'
+            MESSAGE
+        else
+          raise "nothing is raised"
+        end
+      end
+
+      context "given nil to allow any message" do
+        it "contains expected class, actual exception and backtrace when expected class does not match actial class" do
+          expect_raises(ArgumentError, nil) do
+            raise IndexError.new("Index out of bounds")
+          end
+        rescue e : Spec::AssertionFailed
+          e.message.as(String).should contain(<<-MESSAGE)
+            Expected ArgumentError
+                 got IndexError with message: "Index out of bounds"
+            Backtrace:
+              # spec/std/spec/expectations_spec.cr:#{__LINE__ - 7}:13 in '->'
+            MESSAGE
+        else
+          raise "nothing is raised"
+        end
+      end
+    end
   end
 end

src/spec/expectations.cr

@@ -410,32 +410,72 @@ module Spec
           raise ex
         end
 
-        ex_to_s = ex.to_s
-        case message
-        when Regex
-          unless (ex_to_s =~ message)
-            backtrace = ex.backtrace.join('\n') { |f| "  # #{f}" }
-            fail "Expected #{klass} with message matching #{message.pretty_inspect}, " \
-                 "got #<#{ex.class}: #{ex_to_s}> with backtrace:\n#{backtrace}", file, line
+        case {ex.message, message}
+        when {String, Regex}
+          unless ex.message =~ message
+            expectation_failed_message = build_expectation_failed_message(klass, message, ex)
+            fail expectation_failed_message, file, line
           end
-        when String
-          unless ex_to_s.includes?(message)
-            backtrace = ex.backtrace.join('\n') { |f| "  # #{f}" }
-            fail "Expected #{klass} with #{message.pretty_inspect}, got #<#{ex.class}: " \
-                 "#{ex_to_s}> with backtrace:\n#{backtrace}", file, line
+        when {String, String}
+          unless ex.message == message
+            expectation_failed_message = build_expectation_failed_message(klass, message, ex)
+            fail expectation_failed_message, file, line
           end
-        when Nil
+        when {_, Nil}
           # No need to check the message
         end
 
         ex
       rescue ex
-        backtrace = ex.backtrace.join('\n') { |f| "  # #{f}" }
-        fail "Expected #{klass}, got #<#{ex.class}: #{ex}> with backtrace:\n" \
-             "#{backtrace}", file, line
+        expectation_failed_message = build_expectation_failed_message(klass, ex)
+        fail expectation_failed_message, file, line
       else
         fail "Expected #{klass} but nothing was raised", file, line
       end
+
+      private def build_expectation_failed_message(klass : Class, message : String, exception : Exception)
+        backtrace = exception.backtrace.join('\n') { |f| "  # #{f}" }
+
+        <<-MESSAGE
+        Expected #{klass} with message containing: #{message.inspect}
+             got #{exception.class} with message: #{exception.message.inspect}
+        Backtrace:
+        #{backtrace}
+        MESSAGE
+      end
+
+      private def build_expectation_failed_message(klass : Class, message : Regex, exception : Exception)
+        backtrace = exception.backtrace.join('\n') { |f| "  # #{f}" }
+
+        <<-MESSAGE
+        Expected #{klass} with message matching: #{message.inspect}
+             got #{exception.class} with message: #{exception.message.inspect}
+        Backtrace:
+        #{backtrace}
+        MESSAGE
+      end
+
+      private def build_expectation_failed_message(klass : Class, message : Nil, exception : Exception)
+        backtrace = exception.backtrace.join('\n') { |f| "  # #{f}" }
+
+        <<-MESSAGE
+        Expected #{klass} with any message
+             got #{exception.class} with message: #{exception.message.inspect}
+        Backtrace:
+        #{backtrace}
+        MESSAGE
+      end
+
+      private def build_expectation_failed_message(klass : Class, exception : Exception)
+        backtrace = exception.backtrace.join('\n') { |f| "  # #{f}" }
+
+        <<-MESSAGE
+        Expected #{klass}
+             got #{exception.class} with message: #{exception.message.inspect}
+        Backtrace:
+        #{backtrace}
+        MESSAGE
+      end
     {% end %}
   end