From b0095153fcd7f7cdda3441f482fe80af53ff9539 Mon Sep 17 00:00:00 2001
From: Jonathan Bernard <jonathan@jdbernard.com>
Date: Fri, 9 Jan 2026 10:35:02 -0600
Subject: [PATCH] Read slfmt.config.json by default if present.

---
 slfmt.nimble  |  2 +-
 src/slfmt.nim | 37 +++++++++++++++++++++++++++----------
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/slfmt.nimble b/slfmt.nimble
index 9a24a29..e9e882c 100644
--- a/slfmt.nimble
+++ b/slfmt.nimble
@@ -1,6 +1,6 @@
 # Package
 
-version       = "1.0.0"
+version       = "1.0.1"
 author        = "Jonathan Bernard"
 description   = "Small utility to pretty-print strucutured logs."
 license       = "MIT"
diff --git a/src/slfmt.nim b/src/slfmt.nim
index 50cb81a..11a1cc8 100644
--- a/src/slfmt.nim
+++ b/src/slfmt.nim
@@ -5,7 +5,7 @@ import cliutils, docopt, timeutils, zero_functional
 from std/logging import Level
 import std/nre except toSeq
 
-const VERSION = "1.0.0"
+const VERSION = "1.0.1"
 
 const USAGE = """Usage:
     slfmt [options]
@@ -47,7 +47,12 @@ Options:
 
     --config <cfgFile>
 
-        Read expectation data from a json config file formatted as follows:
+        Read expectation data from a json config file. slfmt will, by default,
+        try to read from a file named `slfmt.config.json`, but will silently
+        ignore its absence. When --config is passed, slfmt will fail if the
+        named file is not found.
+
+        The config file is expected to be formatted as follows:
 
             [
               {
@@ -315,14 +320,24 @@ proc parseExpectations(args: Table[string, docopt.Value]): seq[Expectation] =
           expected: isExpected,
           count: 0))
 
-  if args["--config"]:
-    let filename = $args["--config"]
-    if not fileExists(filename):
-      stderr.writeLine("slfmt - WARN: " &
-        filename & " does not exist, ignoring")
+  # TODO: Consider refactoring and moving this outside of this function. Right
+  # now the config file is only used to store expectation configuration, but if
+  # that ever changes and we have additional config data then this confuses the
+  # purpose of this function. We should parse the config separately and pass
+  # that into this function to extract expectations.
+  var configFilename = "slfmt.config.json"
+  var configRequired = false
 
+  if args["--config"]:
+    configFilename = $args["--config"]
+    configRequired = true
+
+  if not fileExists(configFilename):
+    if configRequired:
+      raise newException(IOError, configFilename & " does not exist")
+  else: # file exists
     try:
-      let cfg: JsonNode = parseFile(filename)
+      let cfg: JsonNode = parseFile(configFilename)
       for expJson in cfg.getElems:
         var exp = Expectation(
           fieldName: expJson.getOrFail("fieldName").getStr,
@@ -389,8 +404,10 @@ proc parseExpectations(args: Table[string, docopt.Value]): seq[Expectation] =
         result.add(exp)
 
     except:
-      stderr.writeLine("slfmt - WARN: unable to parse config file, ignoring.")
-      stderr.writeLine("slfmt - DEBUG: " & getCurrentExceptionMsg())
+      if not configRequired:
+        stderr.writeLine("slfmt - WARN: unable to parse config file, ignoring.")
+        stderr.writeLine("slfmt - DEBUG: " & getCurrentExceptionMsg())
+      else: raise getCurrentException()
 
 
 proc eraseAndWriteLine(f: File, s: string) =