acc: Support custom replacements (#2231)

## Changes
- Ability to extend a list of replacements via test.toml
- Modify selftest to both demo this feature and to get rid of sed on
Windows.

## Tests
Acceptance tests. I'm also using it
https://github.com/databricks/cli/pull/2213 for things like pid.

acceptance/acceptance_test.go

@@ -190,6 +190,7 @@ func runTest(t *testing.T, dir, coverDir string, repls testdiff.ReplacementsCont
 	}
 
 	repls.SetPathWithParents(tmpDir, "$TMPDIR")
+	repls.Repls = append(repls.Repls, config.Repls...)
 
 	scriptContents := readMergedScriptContents(t, dir)
 	testutil.WriteFile(t, filepath.Join(tmpDir, EntryPointScript), scriptContents)

acceptance/config_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/BurntSushi/toml"
+	"github.com/databricks/cli/libs/testdiff"
 	"github.com/stretchr/testify/require"
 )
 
@@ -24,6 +25,10 @@ type TestConfig struct {
 	// Which OSes the test is enabled on. Each string is compared against runtime.GOOS.
 	// If absent, default to true.
 	GOOS map[string]bool
+
+	// List of additional replacements to apply on this test.
+	// Old is a regexp, New is a replacement expression.
+	Repls []testdiff.Replacement
 }
 
 // FindConfig finds the closest config file.

acceptance/selftest/output.txt

@@ -28,3 +28,8 @@ $TMPDIR/subdir/a/b/c
 
 === Custom output files - everything starting with out is captured and compared
 >>> echo HELLO
+
+=== Custom regex can be specified in [[Repl]] section
+1234
+CUSTOM_NUMBER_REGEX
+123456

acceptance/selftest/script

@@ -15,7 +15,12 @@ trace python3 -c 'import os; print(os.getcwd())'
 
 printf "\n=== Capturing subdir"
 trace mkdir -p subdir/a/b/c
-trace withdir subdir/a/b/c python3 -c 'import os; print(os.getcwd())' | sed 's/\\/\//g'
+trace withdir subdir/a/b/c python3 -c 'import os; print(os.getcwd())'
 
 printf "\n=== Custom output files - everything starting with out is captured and compared"
 trace echo HELLO > out.hello.txt
+
+printf "\n=== Custom regex can be specified in [[Repl]] section\n"
+echo 1234
+echo 12345
+echo 123456

acceptance/selftest/test.toml

@@ -9,3 +9,12 @@
 
 # Disable on Linux
 #linux = false
+
+[[Repls]]
+Old = '\b[0-9]{5}\b'
+New = "CUSTOM_NUMBER_REGEX"
+
+[[Repls]]
+# Fix path with reverse slashes in the output for Windows.
+Old = '\$TMPDIR\\subdir\\a\\b\\c'
+New = '$$TMPDIR/subdir/a/b/c'