Add non-breakable-word-threshold option to line-length rule (#350)

Fixes #327

Signed-off-by: Anders Eknert <anders@styra.com>

bundle/regal/rules/imports/prefer_package_imports.rego

@@ -6,7 +6,6 @@ import future.keywords.contains
 import future.keywords.if
 import future.keywords.in
 
-import data.regal.ast
 import data.regal.config
 import data.regal.result
 

bundle/regal/rules/style/line_length.rego

@@ -9,14 +9,16 @@ import future.keywords.in
 import data.regal.config
 import data.regal.result
 
-report contains violation if {
-	cfg := config.for_rule("style", "line-length")
+cfg := config.for_rule("style", "line-length")
 
+report contains violation if {
 	some i, line in input.regal.file.lines
 
 	line_length := count(line)
 	line_length > cfg["max-line-length"]
 
+	not has_word_above_threshold(line, cfg)
+
 	violation := result.fail(
 		rego.metadata.chain(),
 		{"location": {
@@ -27,3 +29,10 @@ report contains violation if {
 		}},
 	)
 }
+
+has_word_above_threshold(line, conf) if {
+	threshold := conf["non-breakable-word-threshold"]
+
+	some word in split(line, " ")
+	count(word) > threshold
+}

bundle/regal/rules/style/line_length_test.rego

@@ -27,6 +27,42 @@ foo == bar; bar == baz; [a, b, c, d, e, f] := [1, 2, 3, 4, 5, 6]; qux := [q | so
 	}}
 }
 
+test_success_line_too_long_but_non_breakable_word if {
+	r := rule.report with input as ast.with_future_keywords(`
+
+	# Long url: https://www.example.com/this/is/a/very/long/url/that/cannot/be/shortened
+	allow := true
+	`)
+		with config.for_rule as {"level": "error", "max-line-length": 40, "non-breakable-word-threshold": 50}
+
+	r == set()
+}
+
+test_fail_line_too_long_but_below_breakable_word_threshold if {
+	r := rule.report with input as ast.with_future_keywords(`
+
+	# Long url: https://www.example.com/this/is/a/very/long
+	allow := true
+	`)
+		with config.for_rule as {"level": "error", "max-line-length": 40, "non-breakable-word-threshold": 60}
+
+	r == {{
+		"category": "style",
+		"description": "Line too long",
+		"level": "error",
+		"location": {
+			"col": 56,
+			"file": "policy.rego",
+			"row": 10, "text": "\t# Long url: https://www.example.com/this/is/a/very/long",
+		},
+		"related_resources": [{
+			"description": "documentation",
+			"ref": "https://docs.styra.com/regal/rules/style/line-length",
+		}],
+		"title": "line-length",
+	}}
+}
+
 test_success_line_not_too_long if {
 	r := rule.report with input as ast.policy(`allow { "foo" == "bar" }`)
 		with config.for_rule as {"level": "error", "max-line-length": 80}

docs/rules/style/line-length.md

@@ -15,6 +15,13 @@ close to the maximum line length, consider refactoring your policy.
 
 The default maximum line length is 120 characters.
 
+## Exceptions
+
+On a few rare occasions, a single word — like a really long URL in a metadata annotation — can't possibly be made any 
+shorter. Using an ignore directive isn't an option in that context, and ignoring the whole file is rarely what you'll
+want. The `non-breakable-word-threshold` configuration option allows defining a threshold length for when a single word
+should be considered so long that the line length rule should ignore the line entirely.
+
 ## Configuration Options
 
 This linter rule provides the following configuration options:
@@ -27,6 +34,8 @@ rules:
       level: error
       # maximum line length
       max-line-length: 120
+      # if any single word on a line exceeds this length, ignore it
+      non-breakable-word-threshold: 100
 ```
 
 ## Community