Adds opt-in pre-commit hook for format and header checks. (#1062)

- Closes #639.
- Adds swift format configuration that removes lint checks so we can use
`swift lint` to perform format-only tests.
- Adds `check` target that invokes format and header checks.
- Adds pre-commit script that runs `make check`.
- Adds `pre-commit` target that installs the check script as a
pre-commit hook.

## Type of Change
- [ ] Bug fix
- [x] New feature  
- [ ] Breaking change
- [x] Documentation update

## Motivation and Context
Avoids wasting time and commit rewrites.

## Testing
- [x] Tested locally
- [ ] Added/updated tests
- [x] Added/updated docs

.swift-format-nolint

@@ -0,0 +1,68 @@
+{
+  "fileScopedDeclarationPrivacy" : {
+    "accessLevel" : "private"
+  },
+  "indentation" : {
+    "spaces" : 4
+  },
+  "indentConditionalCompilationBlocks" : false,
+  "indentSwitchCaseLabels" : false,
+  "lineBreakAroundMultilineExpressionChainComponents" : false,
+  "lineBreakBeforeControlFlowKeywords" : false,
+  "lineBreakBeforeEachArgument" : false,
+  "lineBreakBeforeEachGenericRequirement" : false,
+  "lineLength" : 180,
+  "maximumBlankLines" : 1,
+  "multiElementCollectionTrailingCommas" : true,
+  "noAssignmentInExpressions" : {
+    "allowedFunctions" : [
+      "XCTAssertNoThrow"
+    ]
+  },
+  "prioritizeKeepingFunctionOutputTogether" : false,
+  "respectsExistingLineBreaks" : true,
+  "rules" : {
+    "AllPublicDeclarationsHaveDocumentation" : false,
+    "AlwaysUseLowerCamelCase" : false,
+    "AmbiguousTrailingClosureOverload" : false,
+    "BeginDocumentationCommentWithOneLineSummary" : false,
+    "DoNotUseSemicolons" : true,
+    "DontRepeatTypeInStaticProperties" : false,
+    "FileScopedDeclarationPrivacy" : false,
+    "FullyIndirectEnum" : false,
+    "GroupNumericLiterals" : false,
+    "IdentifiersMustBeASCII" : false,
+    "NeverForceUnwrap" : false,
+    "NeverUseForceTry" : false,
+    "NeverUseImplicitlyUnwrappedOptionals" : false,
+    "NoAccessLevelOnExtensionDeclaration" : false,
+    "NoAssignmentInExpressions" : false,
+    "NoBlockComments" : false,
+    "NoCasesWithOnlyFallthrough" : false,
+    "NoEmptyTrailingClosureParentheses" : true,
+    "NoLabelsInCasePatterns" : false,
+    "NoLeadingUnderscores" : false,
+    "NoParensAroundConditions" : true,
+    "NoPlaygroundLiterals" : false,
+    "NoVoidReturnOnFunctionSignature" : true,
+    "OmitExplicitReturns" : false,
+    "OneCasePerLine" : true,
+    "OneVariableDeclarationPerLine" : true,
+    "OnlyOneTrailingClosureArgument" : false,
+    "OrderedImports" : true,
+    "ReplaceForEachWithForLoop" : false,
+    "ReturnVoidInsteadOfEmptyTuple" : false,
+    "TypeNamesShouldBeCapitalized" : false,
+    "UseEarlyExits" : false,
+    "UseLetInEveryBoundCaseVariable" : false,
+    "UseShorthandTypeNames" : true,
+    "UseSingleLinePropertyGetter" : true,
+    "UseSynthesizedInitializer" : false,
+    "UseTripleSlashForDocumentationComments" : true,
+    "UseWhereClausesInForLoops" : false,
+    "ValidateDocumentationComments" : false
+  },
+  "spacesAroundRangeFormationOperators" : false,
+  "tabWidth" : 2,
+  "version" : 1
+}

BUILDING.md

@@ -118,3 +118,7 @@ To revert to using the Containerization dependency from your `Package.swift`:
     bin/container system stop
     bin/container system start
     ```
+
+## Pre-commit hook
+
+Run `make pre-commit` to install a pre-commit hook that ensures that your changes have correct formatting and license headers when you run `git commit`.

Makefile

@@ -186,6 +186,7 @@ integration: init-block
 		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLICreateCommand || exit_code=1 ; \
 		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLIRunCommand1 || exit_code=1 ; \
 		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLIRunCommand2 || exit_code=1 ; \
+		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLIRunCommand3 || exit_code=1 ; \
 		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLIStatsCommand || exit_code=1 ; \
 		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLIImagesCommand || exit_code=1 ; \
 		$(SWIFT) test -c $(BUILD_CONFIGURATION) $(SWIFT_CONFIGURATION) --filter TestCLIRunBase || exit_code=1 ; \
@@ -202,12 +203,19 @@ integration: init-block
 .PHONY: fmt
 fmt: swift-fmt update-licenses
 
+.PHONY: check
+check: swift-fmt-check check-licenses
+
 .PHONY: swift-fmt
 SWIFT_SRC = $(shell find . -type f -name '*.swift' -not -path "*/.*" -not -path "*.pb.swift" -not -path "*.grpc.swift" -not -path "*/checkouts/*")
 swift-fmt:
 	@echo Applying the standard code formatting...
 	@$(SWIFT) format --recursive --configuration .swift-format -i $(SWIFT_SRC)
 
+swift-fmt-check:
+	@echo Applying the standard code formatting...
+	@$(SWIFT) format lint --recursive --strict --configuration .swift-format-nolint $(SWIFT_SRC)
+
 .PHONY: update-licenses
 update-licenses:
 	@echo Updating license headers...
@@ -220,6 +228,15 @@ check-licenses:
 	@./scripts/ensure-hawkeye-exists.sh
 	@.local/bin/hawkeye check --fail-if-unknown
 
+.PHONY: pre-commit
+pre-commit:
+	cp Scripts/pre-commit.fmt .git/hooks
+	touch .git/hooks/pre-commit
+	cat .git/hooks/pre-commit | grep -v 'hooks/pre-commit\.fmt' > /tmp/pre-commit.new || true
+	echo 'PRECOMMIT_NOFMT=$${PRECOMMIT_NOFMT} $$(git rev-parse --show-toplevel)/.git/hooks/pre-commit.fmt' >> /tmp/pre-commit.new
+	mv /tmp/pre-commit.new .git/hooks/pre-commit
+	chmod +x .git/hooks/pre-commit
+
 .PHONY: serve-docs
 serve-docs:
 	@echo 'to browse: open http://127.0.0.1:8000/container/documentation/'

Tests/CLITests/Subcommands/Run/TestCLIRunCommand.swift

@@ -401,6 +401,16 @@ class TestCLIRunCommand2: CLITest {
             return
         }
     }
+}
+
+class TestCLIRunCommand3: CLITest {
+    func getTestName() -> String {
+        Test.current!.name.trimmingCharacters(in: ["(", ")"]).lowercased()
+    }
+
+    func getLowercasedTestName() -> String {
+        getTestName().lowercased()
+    }
 
     @Test func testRunCommandDefaultResolvConf() throws {
         do {

scripts/pre-commit.fmt

@@ -0,0 +1,16 @@
+#! /bin/bash -e
+
+setup_error() {
+    echo failed to run: $1 1>&2
+    echo run '"make pre-commit"' and try again 1>&2
+    exit 1
+}
+
+if [ ! -z "${PRECOMMIT_NOFMT}" ] ; then
+    exit 0
+fi
+
+echo checking formatting and licenses 1>&2
+project_pathname=$(git rev-parse --show-toplevel)
+cd "${project_pathname}"
+make check