Assure files are truncated when we don't append to them!

VERSION

@@ -1 +1 @@
-4.0.5
+4.0.6

lib/tools/src/substitute/spec.rs

@@ -49,6 +49,7 @@ impl StreamOrPath {
                 Box::new(
                     OpenOptions::new()
                         .create(true)
+                        .truncate(!append)
                         .write(true)
                         .append(append)
                         .open(p)

release.md

@@ -1,3 +1,8 @@
+### V4.0.6: Dependency Update
+
+* Assure writes to a single unique output file will overwrite its complete content during substitution.
+    * Previously, if you would write less than the original file size, parts of the previous content may still be present.
+
 ### V4.0.5: Dependency Update
 
 * upgrade all dependencies to the latest version

tests/included-stateless-substitute.sh

@@ -93,7 +93,7 @@ title "'substitute' subcommand"
 
 (with "stdin for data"
   (with "input as yaml"
-    (with "multiple template from a file to the same output file"
+    (with "multiple (2) template from a file to the same output file"
       (sandbox
         (with "the default document separator"
           it "succeeds" && {
@@ -106,7 +106,7 @@ title "'substitute' subcommand"
             expect_snapshot "$snapshot/data-stdin-yaml-multi-template-to-same-file-output" output
           }
         )
-        (when "writing to the same output file again"
+        (when "writing to the same output file again (1)"
           it "succeeds" && {
             echo "the-answer: 42" | \
             WITH_SNAPSHOT="$snapshot/data-stdin-yaml-multi-template-to-same-file-again" \
@@ -130,6 +130,31 @@ title "'substitute' subcommand"
         )
       )
     )
+    (with "multiple (3) template from a file to the same output file"
+      (sandbox
+        (with "the default document separator"
+          it "succeeds" && {
+            echo "the-answer: 42" | \
+            WITH_SNAPSHOT="$snapshot/data-stdin-yaml-multi-template-to-same-file-more" \
+            expect_run $SUCCESSFULLY "$exe" substitute "$template/the-answer.hbs:output" "$template/the-answer.hbs:output" "$template/the-answer.hbs:output"
+          }
+
+          it "produces the expected output, which is a single document separated by the document separator" && {
+            expect_snapshot "$snapshot/data-stdin-yaml-multi-template-to-same-file-more-output" output
+          }
+        )
+        (when "writing to the same output file again (2)"
+          it "succeeds" && {
+            echo "the-answer: 42" | \
+            WITH_SNAPSHOT="$snapshot/data-stdin-yaml-multi-template-to-same-file-again-more" \
+            expect_run $SUCCESSFULLY "$exe" substitute "$template/the-answer.hbs:output" "$template/the-answer.hbs:output"
+          }
+          it "overwrites the previous output file entirely" && {
+            expect_snapshot "$snapshot/data-stdin-yaml-multi-template-to-same-file-again-more-output" output
+          }
+        )
+      )
+    )
   )
 )
 (with "stdin for templates"

tests/journeys/fixtures/snapshots/substitute/data-stdin-yaml-multi-template-to-same-file-again-more-output

@@ -0,0 +1,5 @@
+<Q>: What is the answer to everything?
+<A>: 42
+
+<Q>: What is the answer to everything?
+<A>: 42

tests/journeys/fixtures/snapshots/substitute/data-stdin-yaml-multi-template-to-same-file-again-output

@@ -1,5 +1,2 @@
 <Q>: What is the answer to everything?
 <A>: 42
-
-<Q>: What is the answer to everything?
-<A>: 42

tests/journeys/fixtures/snapshots/substitute/data-stdin-yaml-multi-template-to-same-file-more-output

@@ -0,0 +1,8 @@
+<Q>: What is the answer to everything?
+<A>: 42
+
+<Q>: What is the answer to everything?
+<A>: 42
+
+<Q>: What is the answer to everything?
+<A>: 42