Implement noRepeatedSubjectLines

src/domains/rules/NoRepeatedSubjectLines.tests.ts

@@ -0,0 +1,263 @@
+import { describe, expect, it } from "vitest"
+import { fakeCommitFactory } from "#commits/Commit.fixtures.ts"
+import type { Commit } from "#commits/Commit.ts"
+import { fakeConfiguration } from "#configurations/Configuration.fixtures.ts"
+import { commitConcern } from "#rules/concerns/CommitConcern.ts"
+import type { Concerns } from "#rules/concerns/Concern.ts"
+import { noRepeatedSubjectLines } from "#rules/NoRepeatedSubjectLines.ts"
+import type { RuleKey, RuleOptions } from "#rules/Rule.ts"
+import { fakeCommitSha } from "#types/CommitSha.fixtures.ts"
+import type { Vector } from "#types/Vector.ts"
+
+const rule = "noRepeatedSubjectLines" satisfies RuleKey
+const enabled: RuleOptions<typeof rule> = {}
+
+const fakeCommit = fakeCommitFactory(fakeConfiguration())
+
+describe("when verifying a set of multiple commits and some commits have repeated subject lines", () => {
+	const commits: Vector<Commit, 10> = [
+		fakeCommit({ message: "test" }),
+		fakeCommit({ message: "another bugfix" }),
+		fakeCommit({ message: "Upgrade React to 19.2.6" }),
+		fakeCommit({ message: "#15 make some toast" }),
+		fakeCommit({ message: " Tune the kettle" }),
+		fakeCommit({ message: "#15 make some toast" }),
+		fakeCommit({ message: "Label the mystery switch" }),
+		fakeCommit({ message: "#15 make some toast" }),
+		fakeCommit({ message: "Upgrade React to 19.2.6" }),
+		fakeCommit({ message: " Tune the kettle" }),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("raises concerns about the commits with repeated subject lines", () => {
+			expect(actualConcerns).toEqual<Concerns>([
+				commitConcern(rule, commits[5].sha),
+				commitConcern(rule, commits[7].sha),
+				commitConcern(rule, commits[8].sha),
+				commitConcern(rule, commits[9].sha),
+			])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})
+
+describe("when verifying a set of multiple commits and some commits have repeated subject lines differing only by whitespace or case", () => {
+	const commits: Vector<Commit, 12> = [
+		fakeCommit({ message: "test" }),
+		fakeCommit({ message: "another bugfix" }),
+		fakeCommit({ message: "GL-27 Make some toast" }),
+		fakeCommit({ message: "tune the kettle" }),
+		fakeCommit({ message: "AnOtHeR bUgFiX" }),
+		fakeCommit({ message: "GL-27   make  some    toast" }),
+		fakeCommit({ message: "Label the mystery switch" }),
+		fakeCommit({ message: "  GL-27  make some TOAST  " }),
+		fakeCommit({ message: " Tune the kettle" }),
+		fakeCommit({ message: "TEST!!" }),
+		fakeCommit({ message: "tune           the kettle     " }),
+		fakeCommit({ message: "    ANOTHER bugfix" }),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("raises concerns about the commits with repeated subject lines being whitespace- and case-insensitive", () => {
+			expect(actualConcerns).toEqual<Concerns>([
+				commitConcern(rule, commits[4].sha),
+				commitConcern(rule, commits[5].sha),
+				commitConcern(rule, commits[7].sha),
+				commitConcern(rule, commits[8].sha),
+				commitConcern(rule, commits[10].sha),
+				commitConcern(rule, commits[11].sha),
+			])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})
+
+describe("when verifying a set of multiple commits and merge commits have repeated subject lines", () => {
+	const commits: Vector<Commit, 9> = [
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+		fakeCommit({
+			message: "Calibrate the waffle dial",
+			parents: [fakeCommitSha(), fakeCommitSha()],
+		}),
+		fakeCommit({ message: "Calibrate the waffle dial" }),
+		fakeCommit({ message: "install the `PantryDashboard`" }),
+		fakeCommit({
+			message: "install the `PantryDashboard`",
+			parents: [fakeCommitSha(), fakeCommitSha(), fakeCommitSha()],
+		}),
+		fakeCommit({
+			message: "Calibrate the waffle dial",
+			parents: [fakeCommitSha(), fakeCommitSha()],
+		}),
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+		fakeCommit({ message: "install the `PantryDashboard`" }),
+		fakeCommit({
+			message: "install the `PantryDashboard`",
+			parents: [fakeCommitSha(), fakeCommitSha()],
+		}),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("raises concerns about the commits with repeated subject lines, but ignores merge commits", () => {
+			expect(actualConcerns).toEqual<Concerns>([
+				commitConcern(rule, commits[2].sha),
+				commitConcern(rule, commits[6].sha),
+				commitConcern(rule, commits[7].sha),
+			])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})
+
+describe("when verifying a set of multiple commits and revert commits have repeated subject lines", () => {
+	const commits: Vector<Commit, 8> = [
+		fakeCommit({ message: "Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+		fakeCommit({ message: 'Revert "upgrade the snack dispenser"' }),
+		fakeCommit({ message: "Revert the snack dispenser manually" }),
+		fakeCommit({ message: "Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+		fakeCommit({ message: 'Revert "upgrade the snack dispenser"' }),
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("raises concerns about the commits with repeated subject lines, but ignores commits with revert markers", () => {
+			expect(actualConcerns).toEqual<Concerns>([
+				commitConcern(rule, commits[4].sha),
+				commitConcern(rule, commits[5].sha),
+				commitConcern(rule, commits[7].sha),
+			])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})
+
+describe("when verifying a set of multiple commits and squash commits have repeated subject lines", () => {
+	const commits: Vector<Commit, 12> = [
+		fakeCommit({ message: "Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "fixup! Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "test" }),
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+		fakeCommit({ message: "squash! Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "fixup! Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "upgrade the snack dispenser" }),
+		fakeCommit({ message: "fixup! squash! Refactor the office playlist scheduler" }),
+		fakeCommit({ message: "test" }),
+		fakeCommit({ message: "amend!test" }),
+		fakeCommit({ message: "amend!amend!test" }),
+		fakeCommit({ message: "  Test" }),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("raises concerns about the commits with repeated subject lines, but ignores commits with squash markers", () => {
+			expect(actualConcerns).toEqual<Concerns>([
+				commitConcern(rule, commits[6].sha),
+				commitConcern(rule, commits[8].sha),
+				commitConcern(rule, commits[11].sha),
+			])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})
+
+describe("when verifying a set of multiple commits and some commits have repeated subject lines, but different issue links", () => {
+	const commits: Vector<Commit, 4> = [
+		fakeCommit({ message: "#1 replace guesswork with a tiny chart" }),
+		fakeCommit({ message: "#2 replace guesswork with a tiny chart" }),
+		fakeCommit({ message: "#1 replace guesswork with a tiny chart" }),
+		fakeCommit({ message: "#3 replace guesswork with a tiny chart" }),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("raises concerns about the commits with repeated subject lines, but ignores commits with different issue links", () => {
+			expect(actualConcerns).toEqual<Concerns>([commitConcern(rule, commits[2].sha)])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})
+
+describe("when verifying a set of multiple commits and no commits have repeated subject lines", () => {
+	const commits: Vector<Commit, 10> = [
+		fakeCommit({ message: "init" }),
+		fakeCommit({ message: "Install the pastry metrics panel" }),
+		fakeCommit({ message: "bugfix, sorry!!" }),
+		fakeCommit({ message: "replace guesswork with a tiny chart" }),
+		fakeCommit({ message: "Bring order to the button drawer" }),
+		fakeCommit({ message: "fixup! Bring order to the button drawer" }),
+		fakeCommit({ message: "fixup! Bring order to the button drawer" }),
+		fakeCommit({ message: " explain why the build needs socks" }),
+		fakeCommit({ message: "Test 1 2 3" }),
+		fakeCommit({ message: "fixup! replace guesswork with a tiny chart" }),
+	]
+
+	describe("and the rule is enabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, enabled)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+
+	describe("and the rule is disabled", () => {
+		const actualConcerns = noRepeatedSubjectLines(commits, null)
+
+		it("does not raise any concerns", () => {
+			expect(actualConcerns).toEqual<Concerns>([])
+		})
+	})
+})

src/domains/rules/NoRepeatedSubjectLines.ts

@@ -1,15 +1,51 @@
-import type { Commit, Commits } from "#commits/Commit.ts"
+import type { Commits } from "#commits/Commit.ts"
+import type { TokenisedLine } from "#commits/tokens/Token.ts"
+import { commitConcern } from "#rules/concerns/CommitConcern.ts"
 import type { Concern, Concerns } from "#rules/concerns/Concern.ts"
 import type { RuleKey } from "#rules/Rule.ts"
 import type { EmptyObject } from "#types/EmptyObject.ts"
-import { notNullish } from "#utilities/Arrays.ts"
+import { collapseWhitespace } from "#utilities/Strings.ts"
 
-const _rule = "noRepeatedSubjectLines" satisfies RuleKey
+const rule = "noRepeatedSubjectLines" satisfies RuleKey
 
+/**
+ * Verifies that each commit has a unique subject line within the branch.
+ *
+ * Commits that repeat a subject line are probably meant to be squash commits or the author may have forgotten to update the subject line.
+ * Rewording commits or combining squash commits with their ancestors makes the commit history cleaner and easier to read.
+ *
+ * It is whitespace- and case-insensitive.
+ * It ignores merge commits, revert commits, and commits with squash markers.
+ */
 export function noRepeatedSubjectLines(commits: Commits, options: EmptyObject | null): Concerns {
-	return options !== null ? commits.map(verifyCommit).filter(notNullish) : []
+	return options !== null ? [...verifyCommits(commits)] : []
 }
 
-function verifyCommit(_commit: Commit): Concern | null {
-	throw new Error("The `noRepeatedSubjectLines` rule has not been implemented yet") // TODO: To be implemented.
+function* verifyCommits(commits: Commits): Generator<Concern> {
+	const previousSubjectLines = new Set<string>()
+
+	for (const commit of commits) {
+		const normalisedSubjectLine = getNormalisedSubjectLine(commit.subjectLine)
+
+		if (normalisedSubjectLine !== null) {
+			if (previousSubjectLines.has(normalisedSubjectLine) && !commit.isMergeCommit) {
+				yield commitConcern(rule, commit.sha)
+			}
+			previousSubjectLines.add(normalisedSubjectLine)
+		}
+	}
+}
+
+function getNormalisedSubjectLine(subjectLine: TokenisedLine): string | null {
+	const significantText: Array<string> = []
+
+	for (const token of subjectLine) {
+		if (token.type === "revert-marker" || token.type === "squash-marker") {
+			return null
+		}
+
+		significantText.push(collapseWhitespace(token.value.trim()).toLowerCase())
+	}
+
+	return significantText.join("")
 }

src/domains/rules/reports/CommitwiseReport.tests.ts

@@ -116,6 +116,53 @@ describe("when 'noMergeCommits' has a concern about the commit with a long subje
 	})
 })
 
+describe("when 'noRepeatedSubjectLines' has a concern about the commit", () => {
+	const configuration = fakeConfiguration()
+	const fakeCommit = fakeCommitFactory(configuration)
+
+	const commit = fakeCommit({
+		sha: "8c1fbd48d21686c574a01fd2db4be1c991d897",
+		message: "test",
+	})
+	const concern = commitConcern("noRepeatedSubjectLines", commit.sha)
+
+	it("describes the rule violation in the commit", () => {
+		const actualOutput = commitwiseReport([concern], [commit], configuration)
+		expect(actualOutput).toBe(
+			`
+8c1fbd4 test
+      ╭─────
+      ╰─ Commits must have unique subject lines within a branch.
+         (noRepeatedSubjectLines)
+`.trim(),
+		)
+	})
+})
+
+describe("when 'noRepeatedSubjectLines' has a concern about the commit with a long subject line", () => {
+	const configuration = fakeConfiguration()
+	const fakeCommit = fakeCommitFactory(configuration)
+
+	const commit = fakeCommit({
+		sha: "f3359c9a89b46736a36fa2117515af2f5c93",
+		message:
+			"GH-246 Replace guesswork with a tiny chart and upgrade the `ButterflyService` to 8.0.31",
+	})
+	const concern = commitConcern("noRepeatedSubjectLines", commit.sha)
+
+	it("describes the rule violation in the commit", () => {
+		const actualOutput = commitwiseReport([concern], [commit], configuration)
+		expect(actualOutput).toBe(
+			`
+f3359c9 GH-246 Replace guesswork with a tiny chart and upgrade the \`ButterflyService\` to 8.0.31
+      ╭────────────────────────────────────────────────────────────────────────────────────────
+      ╰─ Commits must have unique subject lines within a branch.
+         (noRepeatedSubjectLines)
+`.trim(),
+		)
+	})
+})
+
 describe("when 'noRevertRevertCommits' has a concern about characters 0-16 of the subject line", () => {
 	const configuration = fakeConfiguration()
 	const fakeCommit = fakeCommitFactory(configuration)

src/domains/rules/reports/CommitwiseReport.ts

@@ -157,7 +157,7 @@ function getRuleMessage(rule: RuleKey, configuration: Configuration): RuleMessag
 			return ruleMessage("Merge commits are not allowed.")
 		}
 		case "noRepeatedSubjectLines": {
-			throw new Error(`Not implemented yet: ${rule}`)
+			return ruleMessage("Commits must have unique subject lines within a branch.")
 		}
 		case "noRestrictedFooterLines": {
 			throw new Error(`Not implemented yet: ${rule}`)