Add Lint/SpecFilename rule

spec/ameba/rule/lint/spec_filename_spec.cr

@@ -0,0 +1,36 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Lint
+  subject = SpecFilename.new
+
+  describe SpecFilename do
+    it "passes if filename is correct" do
+      expect_no_issues subject, code: "", path: "spec/foo_spec.cr"
+      expect_no_issues subject, code: "", path: "spec/foo/bar_spec.cr"
+    end
+
+    it "fails if filename is wrong" do
+      expect_issue subject, <<-CRYSTAL, path: "spec/foo.cr"
+
+        # ^{} error: Spec filename should have `_spec` suffix: foo_spec.cr, not foo.cr
+        CRYSTAL
+    end
+
+    context "properties" do
+      context "#ignored_dirs" do
+        it "provide sane defaults" do
+          expect_no_issues subject, code: "", path: "spec/support/foo.cr"
+          expect_no_issues subject, code: "", path: "spec/fixtures/foo.cr"
+          expect_no_issues subject, code: "", path: "spec/data/foo.cr"
+        end
+      end
+
+      context "#ignored_filenames" do
+        it "ignores spec_helper by default" do
+          expect_no_issues subject, code: "", path: "spec/spec_helper.cr"
+          expect_no_issues subject, code: "", path: "spec/foo/spec_helper.cr"
+        end
+      end
+    end
+  end
+end